I think Feb 24 is as elevated as it is going to get. 12 days is actually pretty fast for turbotax.
The normal backstory for all of this is that once the IRS releases a final version of a form, it has to be programmed, tested by Turbotax, submitted to the IRS for review, and approved again by the IRS. The IRS has to know that the XML file Turbotax is submitting conforms to their specifications and that all the calculations are correct. (Otherwise, the IRS would use expedited handling for Turbotax returns and they would take 6-8 weeks instead of 3 weeks.)
For form 8915-E specifically, the IRS is not allowing the form to be e-filed as an XML file, because their system can't be programmed for it in time. So the information either has to be coded as a text statement called a "General Dependency" or the form has to be attached as a PDF. That also takes time to develop, code, test, verify, and submit for approval. You would not want the IRS to reject your return for lack of a proper dependency statement.
Even after all that, we have not been told whether returns containing form 8915-E will be processed without human review (the usual process) or will be kicked out for human review, due to the inability of the IRS to program their system to accept the form in the usual manner. So no matter when you submit, it might not be processed in time for a hypothetical future payment to be based on your 2020 return.
