Booster and covid

[Thirstquenching]

Hi does anyone know why you have to wait a month between being covid positive and getting your booster?

I heard something on the radio about that today - in laymans terms I guess because your immune system is still fighting off the virus even though you're no longer infectious and your immune system/body needs time to recover.

I tried to Google it and the only thing I could find was that there would be no definition between lingering symptoms of covid and possible side effects of the booster??