We use if to introduce a possible or unreal situation or condition. We use when to refer to the time of a future situation or condition that we are certain of:

You can only go in if you’ve got your ticket.

When I’m older, I’d love to be a dancer.

To talk about situations and conditions that are repeated or predictable, we can use either if or when + present verb form:

You can drive if you’re 17.

If you don’t add enough wood, the fire goes out.

When we go camping, we usually take two tents.

She gets out of breath easily when she’s jogging.