I have given up trying to enforce my payment terms on other (generally bigger) companies. What I do do without fail is ask what the payment terms are before accepting the booking, which means I can make a descision if I accept those terms, or bump up my quote to allow for a particulalrly long payment period.
This year for instance, I have encountered the following.
30 days from receipt of invoice. Been working for these guys for years, and it is always exactly 30 days without fail.
Invoice by 15th of month, paid on last working day of month. It does mean jobs in the last couple of weeks of a month go over 30 days, but I can live with it.
Payment on last day of month following month of invoice. Can mean an almost 60 day wait, but they are charged a small premium!
Payment on receipt of invoice. I like this customer! Earlier this year, I was phoned while on a train back from a gig and asked why my invoice wasn't in yet.
75% 60 days in advance, 25% day after load out. American client, apparently it's what they do with all suppliers.
So it does vary, I just make sure I am happy with their terms. I did turn down a job last year because their terms were 90 days and they quibbled about every penny.