Its a couple month long project. I have seed funding and am fairly well known in the programming community so I have good 'credit'. I'm not against paying upf

Its a couple month long project. I have seed funding and am fairly well known in the programming community so I have good 'credit'. I'm not against paying upfront I just thought it was weird because I always bill for my time, how can someone charge up front if they haven't done any work?