Re: Received $600 for a $1200 consulting gig: need advice

This is probably a bit late.
But next time you get a new client OR
change terms with an existing one, ues a proposal form
that describes EXACTLY what you will be doing,
for whom, for how much paid when.  Both of you sign off on it.
Have his PO reference the proposal/project number and viola,
you have a clearly defined scope of work and he has a clearly
defined payment schedule.

NOW since you didn't get that up front, suck it up and do the work.
Yes you will be a 1/2 week behind when you get paid for the first 2
weeks of the contract, but the way you described it, you didn't demand
2 weeks in advance, just payment in advance, and he gave you
1 1/2 weeks in advance.  I really see how he can be convinced that he is
on the moral high ground.

Scott