It depends, honestly. If you talk to me before hand and are like "i have wait time of a month and a half, is that okay?" and i agree then i see no problem. On the other hand if I commission someone and they dont tell me anything about expected waiting time or anything, i get anxious once a week hits. Specially bad when they dont have a visible queue. To me, as long as you let me know before hand, any time is acceptable.

I see most people accept up to a few months of 0 progress to then send a message, usually a turn around of a few weeks is considered pretty good. I suggest to most people to not wait longer than 6 months for typical art commissions (not large projects or fursuits as they may reasonably take longer) as that's paypal's chargeback window. If you aren't getting any progress or WIPs by 5 months, some red flags would be going up imo

I find a good turnaround time is 2-4 weeks, with a 6 week maximum -- I try to do that for my commissioners and like that when I commission other artists. Obviously the more I've paid for it, the sooner I'd like it delivered, or at least the higher quality, but I am willing to wait for months for a piece if stuff comes up.

If you're upfront about it and are steady in communication, I have no issues with the wait.

I don't have issues with turn-around times as long as there's communication every month or so about progress, and it's obvious the person isn't just taking more and more commissions that they don't seem to be finishing... that last one is sadly extremely common on this site.

Waits longer than 6 months are off-putting for me now, though, as I had someone string me along for over a year before telling me they wouldn't give me a refund (and didn't do the commission). At that point it was out of PayPal's 6 month dispute range.

Within a week: wow, fast turnaround, I would be impressed
Within 2 weeks: great, would be very pleased
Within 3 weeks: sure, that's an average sort of turnaround
After that if I have to wait more than 6 weeks I'll probably send a note (unless they updated me via note or posting a journal)^^
But if they communicated regularly I wouldn't mind waiting up to 12 weeks (like "hey I haven't forgotten about you, here's a sketch for now" or "I have 2 things on my queue ahead of you, then I will start your comm") but would prefer not to wait this long.

I allow all artists 2 months before I reach out for a status update. I might be generous though. You're one of the fastest artists I've commissioned, a big reason I keep coming back!

As long as it takes you less than 2 months to complete a piece, I'd say you're doing pretty good! Any longer and people start to get fairly impatient, especially if you're continuing to take on more work in that time.

oh gosh that heavily depends
if the person has a to-do list and assuming the order of the list is the order they work on then i'd say probably 2 weeks to 5 weeks top (if the list is long) before I ask about the status of the commission
generally I like being given a sketch update (idc if its really rough or cleaned up its just nice to know when the sketch has been started)
after seeing a sketch uhh I'd say a month or 2 months (again it heavily depends on how busy they are before i feel the need to ask if there is any progress)

tho to be honest if I'm given frequent updates (how ever small the progress may be) and good communication I honestly wouldn't really care if it took 6 months or more as long as I know they person is gradually working on it

even when I do my own commissions on my to-do list I add what part of the commission i'm working on (sketch, clean up, line art, coloring ect) and usually note an update at each stage to the person (tho its more so for myself to see if anything needs to be fixed/changed cause I rather do it during the process rather than once i'm finished)