if the condo still under master title means the developer hasn't subdivide the units yet, no strata title yet
if strata title has been issued and current owner has yet to get the strata title transferred to him/her, and if he/she wants to sell the property, then will need consent from the developer for direct transfer
if the owner has already applied for the strata title and in the midst of obtaining it, then this process has to be completed, no half way
you can put a condition precedent in the s&p  - receipt of the copy of strata title duly registered in the name of the seller, so your 3 months will only start after this condition has been fulfilled..
bear in mind your waiting time to get the place will likely cross 3 months (including the waiting time for seller's strata title)
this happened to me all the best