Form and rules
How it works
1
First conditional commonly uses if + present, will + base verb for a realistic future possibility.
2
Other result modals are possible: If you finish early, you can leave.
3
After when, as soon as, before, after, until and unless with future meaning, use present forms rather than will.
4
Use present perfect in a future time clause when completion matters: I'll call you when I've finished.
5
Unless means if not; avoid adding another negative unless the meaning truly requires it.