So timeline:
RFP drafting: 2022
RFP issuing: 2024
RFP evaluation completing: 2027
L1 negotiations starting: 2029
L1 negotiations completing: 2036
First aircraft deliveries: 2040
That's if HAL and other lobbies do not throw spanners in the works.
The RFP will be issued as soon as it's drafted and approved. So we are talking June/July 2022.
And if we go by MMRCA dates, the process took 4.5 years from RFP to L1. With a June/July release, the same should take us to the end of 2026. Of course, MMRCA was delayed due to the slow pace of technical evaluations. 2.5+ years to shortlist, mid-2008 to early 2011 plus Saab delayed the process by 6 months on their own, which won't be the case this time. The new process is expected to be much faster, so we could say 3 to 3.5 years at best. The L1 decision to be made by 2025-26.
So it's the post L1 negotiations that could kill the program. Generally it should be done within 6 months. If DRAL leads the program for Rafale, then it can be done even before that. If HAL, then you know the drill. For now, we can assume DRAL will lead Rafale.
My estimate is 6 months for RFP, 6 months for paper evals, 2 months for flight evals, 6 months for shortlist and 6 months for price discovery. Add an additional 6 months for delays. So 32 months. If things go well, we could sign the contract well within 3 years.