Hopefully you will get one soon and it isn't one of those things they don't bother to notify you about anymore to save on costs.
The last time I renewed my ESA I got nothing from DWP at all. I didn't even get my uprate letter in February, when contacted they said there was no point as nothing had changed and everything was fine! Very annoying. So if you don't hear something within the next week or so, give them 28 days (I know it's a long time for you to wait!) and then contact them and ask.
