If you are still in your F-1 in four months, there shouldn't be a problem in waiting to adjust. You need to be in a lawful US status to adjust from. There shouldn't be issues with not immediately filing for adjustment after receiving I-526 approval (pardon the double negative!).
You may wait the time you desire as long as you are under F-1 status. If your F-1 visa expires in less than 3 or 4 months, you should adjust status prior to its expiration. In order to adjust status you must be under a non-immigrant visa status, in this case F-1.
The filing of an I-485 Application, to adjust in the U.S., for Conditional Permanent Residency, can only occur during the period you are maintaining your non- immigrant F-1 student status.