How much up front?
Enough that a cancel doesn’t cost you.
A 2,400 job with 900 of parts: a 25% deposit still leaves you 300 out if they cancel.
At least cover what you buy before you start.
Questions
Is there a limit on deposits?
Some places cap deposits on some work. Check the rule where you work.
When do I ask for it?
On the quote, so their yes and the deposit come together.
Does the deposit come off the bill?
Yes, the invoice takes it off the balance due.