That depends on the source. Whey protein isolate is, for example, is quicker than steak. But it's not really an issue in the way some imagine it is. If it was we'd all be dead.
Your body starts digesting and absorbing whatever you eat as soon as it's ingested but it takes 2-10 hours to fully digest the protein source depending on which source.
Something like whey is very fast digesting. Something like steak is very slow digesting