I have had a client for about a year, and I did a bunch of work before billing them - they were totally fine with the bill and everything and it wasn't anything too crazy (a couple of thousands of dollars over the course of about 6-8 months of intermittent work). I was a new freelancer and afraid of billing at that point (I've gotten over my fear by now).
Anyway, we agreed to a payment plan of $500/month, due on the first of each month.
I haven't done any work for them this month (not totally crazy, not every month has a lot of work for this client), though there might be a couple of minor items in the backlog that neither I nor the client has prioritized. I also haven't been in communication with them since last payment.
When and how should I gently remind them that payment is due? I've been doing business with them for a year and they've always been good about payment, so I don't want to be TOO much of a stickler for payment on the exact day it is due, especially during a week with a holiday, but I also don't want this to languish too long, especially as they've got several more payments before they are paid off.
Should I maybe ask them if anything needs to be done/mention minor backlog items? Or should I just bring up payment? The latter seems a bit harsh.
How long should I wait after the 1st to bring it up? It's the 3rd now, so not too crazy still, but I feel they either forgot, or "forgot".