It depends on the size of your VMs, their change rate, how many points in time you are keeping, how far apart, etc. There is no formula for this as there are too many variables.
If you want to get an idea, take an average VM for your environment (change rate, size, etc), set the MPIT where you want, run it for the duration (eg. if you are doing 6 points per day for 4 days, you'll need to wait 4 days) and see how big all of the snapshots are at the recovery site.
Does this answer your question?