If it's a new client, we ask for between 20 and 35% up front and 15% upon completion of rough-in. For clients that we have a reasonable relationship with, we ask for nothing up front and then the cost of materials plus some labor after rough-in.
We then do progress billing monthly based on completion (50% complete, we ask for another 25%, 75% complete we ask for 35% or 40%). It also depends on the client as some clients only allow us 15% per month until the job is billed 100%.
State Dependent - Be sure to file the appropriate UUC filings so that you own the equipment until it is fully paid. Integrate this legal stuff in DOCUSIGN. Clients whip though DOCUSIGN and sign these far quicker and with less scrutiny than handing them paper agreements to sign.
In fact - Create an Agreement for each client in advance of doing any work - regardless if you charge for the analysis work or not.
Did some testing, looking at HelloSign too for our low volume needs. Trying to put the whole process as a natural part of the sales, support process.