There is not an exact answer for this as it can depend on the type of medication, the procedure itself, and other factors.
As an example, however, most doctors will instruct you to use them four times a day for a week after IOL (intraocular lens) surgery. For LRI (Limbal Relaxing Incisions) surgery it is usually four times a day for at least two weeks.
However, you need to find out from your doctor exactly what you need to do for your specific situation, and for the specific type of antibiotics that he provides to you. There is a very important reason for this. If you use antibiotic eye drops for less than the optimal amount of time, it may not kill all the bacteria present and cause a far worse condition in your eye.
This is not something you should take lightly and not something you should guess on. You need to get this answer directly from your doctor. The above-stated instructions are just an example of what some doctors will recommend to their patients and should not be taken in any way as instructions that are appropriate for your situation. Talk to your doctor!