When is the most appropriate time to apply sunscreen before going out?

As the weather gets warmer these days and the UV index seems to be rising, I plan to apply sunscreen more thoroughly. However, a question suddenly occurred to me, so I am asking the community members. Is applying it immediately right before going out the most effective way to block the rays? Or should I apply it 30 minutes before leaving, considering the time it takes to absorb into the skin? Everyone has different opinions, so I’m curious to get accurate information.

Some people say you need to reapply frequently to maintain the effect, but honestly, reapplying over makeup isn't easy. I'm curious to hear reviews from those who have used products like sun sticks; would they be okay without causing makeup to smudge? I'm posting this because I know UV rays are the main culprit behind skin aging, and I want to block them completely. If you have any professional know-how, please share even a small tip. I look forward to your comments.