IIRC the H-1B application period is some time in the first half of April every year (so all the ones that would be filed this year have already been filed), but IDK if renewals need to catch that train.

Edit: clarifications.

H-1B approval has two stages, the registration period (March/April) and the petition period (ends 90 days after post-registration selection). AIUI this is counting petitions (i.e. I-129s), so won't be accurate until at least 90 days after selection notices - which would be around now - but then the site itself says it can further trail by a quarter.