Hi debbie,
Although there is no requirement to send the form by recorded delivery, you might wish to consider this. Make sure that you have a copy of the form, and if DWP send a text, but if you have tracked the mail the Post Office might send a text or you can use the number on the website. It usually takes around 10 days for DWP to register and process letters.
As for waiting times, the answer is a long as a piece of string! I have seen delays of 6 months mentioned. I guess it depends on whether there needs to be an assessment. If you are significantly disabled, with strong medical evidence then there shouldn't be a need for one. However DWP often fails to understand a lot of conditions, and therefore still require an assessment anyway!
Have you had your award extended by DWP? Make sure that this has happened. There have been instances where DWP have not done this, and then payments have lapsed before the new/review claim has been determined.
Good luck.
LL26
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
