While there is a lot of debate over the release date, I would say a safe assumption is something like late April to early May (7-10 weeks).
As for if you should wait, I would recommend reading this post:
https://forums.macrumors.com/posts/14364293/
You have not provided enough information to really answer your questions. And In truth, only you can decide what you want.Also if you say buy now or later do you suggest I get the 21.5" or 27" model. I currently have a mid-2010 27" 3.2GHz i3 model.
I've a 2006-06 white plastic 24" iMac, and we use it all day long, from surfing and working on digital photos / videos to games and watching movies / shows to MS Office apps and so on maxed out the RAM years ago, and the horse keeps chugging along. When the new iMac's come out, there will be one coming my way - given that it has the upgrades that I'm hoping for,,, if not, I'll get a refurbed previous [right now current] model. Ours has lasted ~6 years, w/o anything more significant than the RAM upgrade and a logic board a few years ago. Still, if quite fast but I'm eyeing some new photo / video s/w, so therefore the high interest in newer stronger faster better model. YMMV![]()
Why do you want to upgrade?
I think that folks get way over excited over the latest and the greatest thing when what they actually have is working fine for them and then it is also they "just have to have the newest" as if it is a badge of honor. Just my opinion.
Also if you say buy now or later do you suggest I get the 21.5" or 27" model. I currently have a mid-2010 27" 3.2GHz i3 model.