if your return is rejected you can fix and refile. if you didn't have a 1095-A I'm don't know what you entered or where. it may make no difference unless you took tax credits or deductions that you weren't entitled to.
if you did:
and if the IRS doesn't reject your return and sends you a notice you can respond at that time according to the instructions given
or if you get your refund you can amend it at that time
or if you paid then you'll have to wait until your return is fully processed and then amend.