Estate Tax Return

My mother passed away 2/19/2023, I just completed her individual 2023 tax return and now need to follow up with her Estate income tax return 1041.  The only Estate income is the sale of her house that will close on 2/20/2024.  Did I err by not filing an Estate tax 1041 earlier for 2023 or can I just file that once the house closes and the estate is finalized? One and done? What are my actual deadlines for filing? 

We are in CT , does CT have an Estate Income Tax Return?

Thank you