After you file

really nothing to do for the 2019 tax return

 

your child will be able to get the 1st stimulus by completing their 2020 tax return.  Look at Line 30 of Form 1040 when its complete

 

as for the 2nd stimulus, no guidance yet on how that is to occur for those who were a dependent in 2019 and not a dependent in 2020.  Stay tuned! .... and suggest your child not be in a hurry to file the 2020 tax return until the IRS explains what to do!