Just to give an idea here:
There must be about three (?) regiments of the Pinaka system within the IA at this point with plans for one (?) per year raising. (Rohitvats et. al., please correct the numbers here if I am out of date or simply wrong)
So lets assume we have 4 regiments at this point.
Each as 12 launchers.
Each Launcher has 12 tubes for a single salvo.
This means that for a single salvo fire from each of the launchers in the 4 regiments, we need about 576 rockets.
That's just one salvo. Assume that we need each regiment to be able to fire at least (and being outrageously conservative given the needs for modern combat)
nine (

) salvos + 1 reserve salvo.
Then you need 5760 rockets.
Then you need to add a new regiment each year (if we are not at our sanctioned limit already).
So doing 1000/2000 rockets a year is not going to cut it IMVHO.