How long does it take to get a foot fungus? I showered after my boyfriend Monday who has a foot fungus

Be prepared... This all depends on what you mean by "get" a foot fungus. We are surrounded by fungi and exposed to potential infection daily. When the conditions are right, the fungus will thrive. Warm moist areas are the best. The already present spores will activate and begin feasting on your skin within days. Having them and having them infect you are two different things.
Foot fungus. It usually takes within 2 weeks. There are some great preventative natural treatments I recommend if you are concerned.