The delay in IM is acutally due to the wifi driver problem in Jelly beam 4.2 if you are having delay while on wifi. So now only Google can solve it. If you think the delay is unacceptable, solution is to change to your 3G or LTE instead of wifi.
I am on 3G network.
After more observation, i have to enter the app then i can recieve the msg.
If not no msg. Bought it less then a week.
