I'm assuming that this is an 'MC100' form (
https://www.google.com/url?sa=t&sou...MQFnoECBoQAQ&usg=AOvVaw0UcUa6NUbvZFli3DLNGo8V) If you aren't currently working, then say that by filling in the 'if you are NOT employed' boxes.
And there's a box in section 4 for additional information, so as you know you will be working soon mention that in there. Say
- who you will be working for
- when you start
- how many hours you think you will do each week
- how much you expect to be paid each hour. If you don't know how much the tax will be, give the amount before tax and make it clear this is the pay BEFORE TAX.
My guess is that the court will work out the fine on the basis that you have no income, but it's really important that you avoid getting into more trouble so it's best to give them too much information and let them decide what they need to pay attention to.