Easy rule, use wann and wenn.
If you are struggling to understand the difference between the German words wenn & wann, you've come to the right place - or so I hope!
Many learners struggle with these two words not only because they sound super similar, but also because they are used in very similar contexts.
The problem here is, that "wenn" is normally translated as "if". But this sentence doesn't mean "I'll do it, if I get home".