How far in advance do you apply sunscreen before going out?

This is something I've always wondered about whenever I apply sunscreen, haha. Do you all apply it right before going out, or do you apply it well in advance? I usually tend to swipe it on quickly right before leaving, but I don't think that's a good idea... just my guess...

I heard somewhere that it takes at least 20 to 30 minutes for sunscreen to absorb into the skin and form a protective barrier. I was told that you need to apply it well in advance of going out for it to be effective, but getting ready at exactly that time on a busy morning is harder than I thought. When I apply it right before leaving, I also feel a bit uneasy, worrying that I might be directly exposed to UV rays. I'm also curious if there is no protection at all or if the effectiveness simply decreases if I don't apply it in advance. I'd like to know at what stage of your routine do you all apply sunscreen?