Hi Megan
It's up to you when you send it back - just as long as it arrives in plenty of time.
I cannot tell you how long it is taking to deal with reviews or decisions because even before the current crisis - there was a backlog of cases. Many people have been waiting as long as 9 - 14 weeks. Best case scenario 6 weeks. But at the current time it is all speculation.
If they do a telephone interview - someone will ring you up and go through your form and any other additional questions they have.
If there is no telephone interview a paper-based decision could be made and you will be contacted when that is complete.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
