You could be meaning 2 different things by this question, so I'll answer both ways.
They will first absorb into the skin and then absorb into the bloodstream (if systemic).
One of the benefits of a topical is the more steady state absorption into the bloodstream, which occurs after its absorbed through the skin.
I wouldn't take a shower for at least 2 hours after applying; ideally not for 4 hours.
The way I personally use it is that I use it morning and night. I wait at least 10 minutes after showering in the morning to apply it and then apply it again at night.