I know in my case they just used whatever checks I had at the time.  I'm pretty sure they just averaged my income and decided that's what I would make.  But I've been in court since then to update my income a couple times.  So, as your income changes, I think the other parent is going to come after you anyway, so you might just file yourself after you have an income.  Even if you don't have any commissions, they can still see you are making minimum wage and trying.

I used the worksheet on here and filed my own case.  I'm glad I did because it saved me over $1000.  I don't know if he does this for everyone, but I PM the guy who posted the worksheet and he showed me what to put in the worksheet.  It was pretty easy for my case.  It cost me about $50 at the court house to file it though, but it saved me 1000.

Jeepster,

When you filed with the court do you just fill out your numbers and then the courts ask for the other parents numbers to fill in or do I have to ask for her numbers as well?

@tris you will need both person's numbers to fill out the sheet.  What I did to start out was I sent a certified letter to my ex requesting copies of the last 3 months of pay stubs and also how much for insurance and daycare.  There is a rule in the guidelines that says a parent has 30 days to give that information or they can be penalized.  I think I mentioned that in my letter that I would seek legal expenses if I had to hire an attorney to subpoena the information.  Oh, and you don't need an attorney to subpoena the other parent.  I have done that in the past as well.

I wouldn't suggest filling in your info and filing yet because you don't know anything about the other parent.  So, you should start by asking for the income.  But, they will most likely ask for yours too and they will know that you are getting ready to do something.  Attorneys I have had in the past have used her income on her last child support worksheet.  It will probably increase by 3% per year just like everyone's does.