I have a potential client who has sent me the functional spec for their app idea. The spec is a PPT, which does a pretty good job at specifying the features, design and flow of information within the app. Of course, by just reviewing the spec you cannot be sure to be 100% certain you have acknowledged all requirements.
No contract has been signed, but they are very interested in working with me. We've agreed this would be a fixed-rate contract.
I'm considering suggesting to meet with their team and determine all requirements based on the spec. This seems like a lot of work for both teams (plus I wouldn't be paid yet) and something that should only be done after the contract is signed. Plus, it may turn them off from working with me.
Otherwise, does it make sense to send them a proposal with an estimate based on the spec, sign a service agreement based on the estimate, then meet with their team to formally review requirements in detail, then re-evaluate the cost?
My question is when in the process do you determine the "final" requirements for the project, and when do you determine what to charge for the work?