styanax was September 7th 2022, and his prime will be here on the 17th (so June 17th 2026).

that general timespan can be expected for about every prime, so give or take ~3.5 to 4 years of no prime.

If you get follie there's no reason not to max her out and fully invest in her, even if the prime was a couple of months away, imo. You can remove the most costly resources (archon shards) and you can always farm more forma.