Learn Hardcore Swedish: Ju tidigare vi går hem, desto lugnare blir kvällen. - The earlier we go home, the calmer the evening becomes.

It’s the Swedish way to say “the X-er ..., the Y-er ...”.
First clause starts with ju
- comparative; second clause starts with desto
  - comparative.
Template: Ju + comparative + (subject + verb), desto + comparative + (verb + subject).
Example: Ju tidigare vi går hem, desto lugnare blir kvällen.

Can I switch ju and desto, or use just one of them?

No switching: the first half takes ju, the second desto. You sometimes hear ju ... ju ... in speech, but ju ... desto ... is the standard in writing.
Don’t drop them; Tidigare vi går hem, lugnare blir kvällen is ungrammatical.

Is the comma required between the two halves?

A comma (or a semicolon) is standard to separate the paired clauses: ..., desto .... It’s strongly recommended for clarity.

Why is the word order vi går in the first part but blir kvällen in the second?

The ju-clause is a subordinate clause, so it uses Subject–Verb order: vi går.
The desto-clause is a main clause. Swedish main clauses are V2 (verb in second position). Desto lugnare takes first position, so the verb blir comes next, then the subject kvällen.

Why blir and not är, ska bli, or kommer att bli?

bli expresses a result or change: the evening becomes calmer as a consequence.
Present tense often covers future meaning in Swedish when context is clear, so ... blir kvällen is natural.
... ska/kommer att bli is possible but heavier and less proverbial.

What does hem mean here? Why not till hem? How is hemma different?

hem = to home (direction). No preposition: gå/åka hem.
hemma = at home (location): vara/stanna hemma.
Don’t say till hem. You can say till huset (to the house) if you mean the building.

Does gå hem imply walking, or can it just mean “go home”?

In this fixed phrase, gå hem often simply means “go home.” To specify transport, use åka hem (by vehicle), köra hem (drive), or promenera hem (walk).

What kind of word is tidigare? Why not mer tidig?

tidigare is the regular comparative of tidig (early), formed with -are. It can act as an adjective or an adverb.
Here it’s adverbial (modifies when we go).
mer tidig is possible but sounds unnatural; prefer tidigare.

How is lugnare formed, and does it agree with kvällen?

lugnare is the comparative of lugn (calm), formed with -are.
Comparative adjectives don’t take gender/definiteness endings, even with definite nouns.
- Predicative: Kvällen blir lugnare.
- Attributive: den lugnare kvällen (still no extra ending).

Why is it kvällen (definite) and not kväll?

Swedish uses the definite form for a specific, understood time period (tonight’s evening or the evening in question). Indefinite kväll here would sound odd.

Can I say Ju tidigare vi går hem, desto lugnare blir det?

Yes. det can stand for “the situation/the evening,” making the statement more general. Both versions are idiomatic.

How do I negate this kind of sentence?

Prefer using the opposite comparative instead of inte:
- Ju senare vi går hem, desto mindre lugn blir kvällen.
- Ju senare vi går hem, desto stökigare blir kvällen.
If you use inte, normal placement applies but sounds marked:
- Subclause: Ju tidigare vi inte går hem ...
- Main clause: ... desto lugnare blir inte kvällen.

Can I use other comparatives or quantities with ju ... desto ...?

Yes:
- Adjectives: Ju tröttare vi är, desto tystare blir vi.
- Adverbs: Ju oftare vi ses, desto bättre mår vi.
- Quantities: Ju fler som kommer, desto roligare blir det. / Ju mindre tid vi har, desto snabbare jobbar vi.

Any quick pronunciation tips for tricky words?