But, in all honesty, all RR numbers are estimates. MRR is also a "made up number" from a certain point of view: it is not equivalent to cash received every month, because of annual subscriptions, cancelations, etc.
Sure, but I would expect you to have at least one data point or at least near it, before making any estimates for that timescale. I don't see many people make MRR projections based on 2 days of of sales, it's just something I've noticed with startups and ARR.