WHEN all the forms in your return are ready to file AND you can complete the FILE tab all the way to the end and SUBMIT the return it is sent to a holding room where it waits for the IRS to come and get the return for processing. Once the return is pending at the IRS for processing the return will be frozen and you will not be able to do anything in the tax file in TT ( not even complete the state return) until the IRS either accepts or rejects your return. Do NOT be in a rush to get into the pool ... last time there were major tax reforms many early filer returns got lost/stuck in the IRS system and it took months for those returns to process ... I would NOT file any return until the bugs have been worked out.
NOW ... the IRS has not announced a start date for efiling the 2018 returns and with the current government shutdown it is predicted that it will not start before 2/1/19 SOOOO you have time to wait.