Learn Hardcore Turkish: Toplantı başladığında herkes yerini almıştı; sadece sunucu gecikmişti. - By the time the meeting started, everyone had taken their seats; only the presenter was late.

They are in the Turkish past perfect (pluperfect), formed with -miş + past of “to be” (-ti). It marks actions completed before another past reference point (here: the moment the meeting started).

almıştı = al- (take) + -mış (perfect) + -tı (past “was”) → had taken
gecikmişti = gecik- (be delayed) + -miş + -ti → had been late

Why use -mişti instead of the simple past (-di)?

With -mişti, you say the actions were already completed by the time the meeting started. If you used simple past: Toplantı başladığında herkes yerini aldı; sadece sunucu gecikti. it suggests they took their seats at/after the starting moment, not necessarily before it.

How is başladığında formed, and what does it literally encode?

It’s a time clause meaning “when (it) started,” built like this:

başla- (to start)
-DIK nominalizer → -dığ- (the fact of having started)
3rd person possessive → -ı (ties the action to its subject)
buffer -n (needed before a case suffix)
locative -DA → -da (“at/in”) Putting it together: başla- + -dığ- + -ı + -n + -da → başladığında = “at the time that it started.”

Could I use başlayınca, başladığı zaman, başlarken, or başlar başlamaz instead? What are the nuances?

başlayınca: neutral “when/once it starts/started,” common and a bit more colloquial.
başladığı zaman: “at the time when it started,” explicit and clear.
başlarken: “while it was starting,” overlapping, in-progress nuance.
başlar başlamaz: “as soon as it started,” immediate succession.
başladığında: compact, slightly more formal; good in writing.

Why is it herkes yerini (singular) and not herkes yerlerini (plural)?

Herkes is grammatically singular in Turkish, so you use singular agreement and singular 3rd-person possessive:

Herkes yerini almıştı. (standard) Colloquially, some say herkes yerlerini, but prescriptive grammar and formal writing prefer the singular.

Should the verb agree in singular with herkes?

Yes. Use singular verb forms:

Herkes geldi / almıştı. (not “geldiler / almışlardı”) If you use hepsi (“all of them”), plural agreement is common:
Hepsi geldiler / yerlerini aldılar.

Why is it yerini (accusative) and not yerine (dative)?

Because the idiom is yerini almak (“to take one’s place/seat”), which takes a direct object (accusative).

yerini = yer (place) + 3sg poss -i
- accusative -n(i) With movement verbs, you use the dative:
yerine oturmak / yerine geçmek (“to sit in/go to one’s place”)

Is yerini almak the only way to say “take a seat”?

No. Alternatives include:

yerine oturmak (sit in one’s seat)
koltuğuna oturmak (sit in one’s chair)
yerine geçmek (move to one’s spot) Note: yerini almak can also be figurative: “to take (someone’s) place.”

Who is the sunucu exactly? Host, presenter, or speaker?

Sunucu is a presenter/host/MC; on TV it’s a presenter. If you mean the person giving the talk, konuşmacı (speaker) or sunum yapan kişi is clearer. Moderatör is a moderator; spiker is typically a newscaster.

Can I use geç kalmak instead of gecikmek?

Yes. For people, both are fine:

Sunucu gecikmişti / Sunucu geç kalmıştı. Gecikmek often sounds a bit more formal and is also common for things/events (Uçak gecikti = The plane was delayed).

Does the position of sadece matter?

Yes:

Sadece sunucu gecikmişti. = Only the presenter was late. (No one else was late.)
Sunucu sadece gecikmişti. = The presenter had only been late (and nothing worse). So keep sadece immediately before what is being limited.

Why a semicolon here? Could I use a period or a conjunction?

The semicolon neatly links two closely related independent clauses. A period also works:

Toplantı başladığında herkes yerini almıştı. Sadece sunucu gecikmişti. Or use a conjunction with a comma:
…, ama/fakat sadece sunucu gecikmişti.

Do I need a comma after Toplantı başladığında?

Optional. Many writers omit it when the clause is short and unambiguous, but adding a comma is acceptable:

Toplantı başladığında, herkes yerini almıştı; …

Pronunciation tips for tricky letters here?

ı (dotless i): a close, unstressed “uh” sound (as in the second syllable of “sofa”).
ğ: lengthens the preceding vowel; it’s not a hard “g.” In başladığında, the ı is slightly lengthened.
c = “j” in “jam” (su-nu-ju for sunucu).
ş = “sh.”

Could I say Toplantı başladıktan sonra instead of başladığında?

That changes the timing. Başladıktan sonra = “after it started,” implying the seat-taking happened subsequent to the start. The original says the seats had already been taken by the time it started.

Can I move the time clause to the end?

Yes, Turkish allows that, typically with a comma:

Herkes yerini almıştı, toplantı başladığında; sadece sunucu gecikmişti. That said, many prefer the original initial position for flow and clarity.

Does -mişti carry hearsay/evidential meaning here?

No. -miş alone can be evidential, but -mişti functions as the pluperfect (“had done”) marking anteriority to another past point, not reportedness.

What’s the difference between herkes, hepimiz/hepiniz, and hepsi?

herkes = everyone (indefinite, grammatically singular): Herkes yerini almıştı.
hepimiz/hepiniz = all of us/you (1st/2nd person agreement): Hepimiz yerimizi almıştık.
hepsi = all of them (often plural agreement): Hepsi yerlerini almış(lar)dı.