Filling out "Request to Make Payments" form, SC220.. Can I request to change the amount I pay later or is this form final?

I am the Defendant and I lost in small claims a few weeks ago.. Right now I don't make much money at all, but I should start receiving commissions soon. I am filling out form SC-220 and want to put small payments monthly and then a large final balloon payment in 6 months. At this time I think I can fulfill this request.. HOWEVER - I am in sales and things happen! If I don't get the money I am expecting, can I make a request to change this payment arrangement later? I can't seem to find a form online that says request to amend payment arrangement by defendant, of something like that.. Is this an option for me or is my request set in stone if accepted by plaintiff and judge?