What should I do?

Hello everyone,

Hope you're enjoying your summer!

My OPT will expire on Sept.I plan to change my F-1 to F-2 shortly before the expiration.
My hu*****and is gona submit I-140 and I-485 concurrently very soon(end of this July).
My question is:
Should I change F1 to F-2 and get the receipt before I-140 & I-485 submitted.
Or it is ok for me to change to F-2 after my hu*****and's I-140 & I-485 is pending?

Appreciate your reply!