就: what are the top 3 meanings by usage 就 is one of the most widely used word.  From secondary school english student point of view/ general usage/ HSK exam point of view what are the 3 most meanings that covers by usage?
dictionary has 20+ meanings, it is confusing me rather than giving the meaning. the 22 meanings as per pleco are
1 at once
2 right away
3 only
4 just (emphasis)
5 as early as
6 already
7 as soon as
8 then
9 in that case
10 as many as
11 even if
12 to approach
13 to move towards
14 to undertake
15 to engage in
16 to suffer
17 subjected to
18 to accomplish
19 to take advantage of
20 to go with (of foods)
21 with regard to
22 concerning
what are major 3 meanings as per your usage.
Edit: I am updating my Anki entry as below.

then, to move towards, even if, so
soon, right away, as soon as
just, only
Chinese Grammar Wiki classifies the use of 就 into A2, B1, B2, and C1 levels (from easiest to hardest). Begin with the easiest level (就 as 'then', i.e. your 8th entry) – I believe this is its commonest use. Do not bother with harder uses of 就 (e.g. your 21st/22nd entry, which is labelled level B2 on the site) for the time being.

Sometimes you need to learn 就 as part of a word to make sense. E.g.: 就算 (your 11th entry), 就近 (your 13th entry). Sometimes, as part of a sentence construction, e.g., 一～就～ (your 7th entry).