Some people say you should clean your guns as soon as possible after each shooting session. I have done that for many years BUT have also let them sit for months without cleaning them.
Either way, it takes the same amount of time and effort to clean firearms. The fouling does not get harder to remove the longer it sits.
The most important gun cleaning factor is the time you let the gun solvent sit before you brush or patch. I have done many gun cleaning solvent tests and 10 minutes of soaking is the absolute best. 5 minutes does not even come close to 10 minutes. There is a huge difference. Soak your gun action/barrel with plenty of solvent and then set your timer for 10 minutes.