I commissioned a badge from basteki January last year to be completed after FC.
I'm always fine with waiting; I'm patient, but I like to keep updated with artists every 5-6 months. I think that's reasonablewith artists that aren't active online.
I've tried to get in contact with Bastek numerous times. I sent them at least 3 e-mails and have IMed them at least 2 or 3 times on AIM. I still haven't gotten a response and I've been trying to contact them off and on for the last couple of months. I'm not sure if Bastek is MIA or busy; I'm hoping someone here will let me know if something’s up. I've worked with Bastek numerous times in the past and they were always responsive to my inquiries.
Last January, I also purchased a 2-character, pencilwork commission from http://silverbobcat.deviantart.com/. During the inquiry process, they were extremely professional and helpful in setting up the commission details. However, since then I haven't been able to get in contact with SBC. I sent her an e-mail in Feb but never got a response. [I believe I sent her at least 2 e-mails.] They don't seem active on DA and their commission process list hasn't changed since I first commissioned them. Again, if something is up with the artist, please let me know how to get in touch with them.
edit: above two cases have since been resolved! :)
Last October, I commissioned sfinder for an icon set. She had finished some icons and a badge for me in the past with very few problems; I got my artwork in due order. When she started offering her moodicon sets, I commissioned one from her. At the time, she was steadily finishing them. Several people put on the same list as me have already had their sets done. She finished several of them in the next few months or so. In the beginning I contacted her once or twice on IM for updates, which she swiftly gave me and I was happy with. 6 months later, I thought to contact her again. I recently sent her a DA note [which DA tells me she has opened] and several I.M.s trying to get in touch with her. No luck and no response.
Several of the artists I've had good experiences with up to this point. I know things come up, as an artist and a commissioner, it is always best to reply to your customer's e-mails, even if you are busy or stressed. I understand stress and time limit, but if you just reply to your customers letting them know about the delay, at least the customer knows that you still intend to finish the commission at a later date. Avoiding your customer's attempts to contact you will only result in stress and misunderstandings with both parties. I always update with my clients on my work progress or at least keep a public work list up to keep them updated. Disappearing off the internet has a tendancy to upset your commissioners. I don't think an update every 6 months or so is unreasonable, even if you can't complete the piece at that time, it's fine. Just let your customers know what's going on. People don't like being left in the dark.
Again, if you know how I can get in contact with any of these artists, please let me know. I appreciate it.
[Edit:] I sent an email and DA note to Starfinder with all my commission details and she responded. She says she intends to finish my commission. I'll let you know what happens in the end, but I'm pleased that she finally replied. :]