IMHO ... if it's Rafale ... stick with one platform until you get a next-gen/5th-gen fighter option to complement it.
So, start with 16 Rafales, and then with time grow it to the 3-4 squadron strength you were planning on. Once you've fully absorbed that (along with the support systems, e.g., AEW&C, UAVs, etc), then move towards a FGFA: maybe 1-2 squadrons. Basically, and I said this earlier, BAF should pattern its procurement style based on Poland, forget the Indo-Pak line of thinking.
What you say makes sense but BD wants to balance the West and China.It cannot be dependent on either.
Remember BD is a country of 165 million and it's population will peak at 180-200 million in the 2030s.
It sees itself as becoming one of the 10 most powerful countries economically and militarily by mid-century.
BD already has an aerospace company (BAC) and it's first jet trainer is scheduled to fly next year. The first aerospace university has also been set up. This is a country with an ambitious long term plan.
CEBR predicts that it's economy will grow to 25th largest by 2034 and who knows it may enter the top 10 by 2050 but that is too far into the future to predict with much certainty right now.