Hi Michelle, here are some thoughts from my experience
In a corporate environment, when I hired caterers, I expected them to be willing to wait 7-10 days for payment (because the company had a once-a-week check run). If they weren't willing to work within that timeframe I often went with another caterer (I wasn't really able to use 1-person catering companies then).
Individually when I cater, if it's for a large event or a wedding cake or chocolates (for wedding favors or a party), I take a 50% non-refundable deposit at the time of order with the remainder due on delivery (generally, for me, that's the day before or day of the event). I'm not catering for companies, where it can be really inconvenient for them to cut individual checks, or I'd expect to wait 7-10 days for payment. And I don't often cater for strangers anymore, generally only for people I know really well, so I allow for more latitude with the payment schedule. I still take the 50% deposit, it's almost a way of saying 'we're both serious', in order to buy any supplies. That way, if the event is cancelled, I'm not out the cost of foodstuffs.
It's well worth making sure you have the legalese in place, a standard (brief) contract, that you know is enforceable in your state in small claims court. If you both sign it, without any fanfare, then you can cater with an open mind (& heart) knowing you will get paid.