There is no definite answer. The speed at which the Co2 is produced will be directly affected by temperature that it's stored at. It would also depend on the strength of the bottle that you are using. I have done this myself many times using 2L plastic soda bottles and adding 40g of priming sugar to each. I store the bottles at room temperature for four weeks and then chill for a minimum 8 hours before opening and have never had any problems with any of the 200 or so bottles that I've produced. The only concern is that plastic bottles do allow transfer of air and so it's not recommended for storage for more than 1 year.
