Missing Schedule K-1 that will impact my projected refund - what next?

I've completed my taxes and I'm currently scheduled to get a significant federal & state refund.  However, I'm missing a K-1 form that will likely reduce or eliminate the refunds.  The K-1 is expected to be out by 4/18/2023.  Do I file my return now to get the refund and then amend the tax return after the K-1 comes out?

Or do I file for an extension and submit the return once the K-1 is available?  If I end up owing taxes after the K-1 is available, would I be subject to any late fees? 

I typically pay quarterly taxes so how do I account for that in my filing?