Least number of days you need to wait from last year's expiry date you need to wait before applying

Im on student resident permit, and my residence permit from last year expires on the 23rd of august. Usually I re-apply 3-5 days before expiry. But since I'm planning to travel around that time, Im thinking of going to re-apply may be 15-20 days ahead. Is that ok? or should i only re-apply least 5 days before date of expiry.

Usually, according to the rules, how long ahead can I go for application from the date of expiry?