Hi NKT0817,
Accra will send an email (only to the principal applicant's email) when they have started processing your application in Accra. For us this took just over 2 months time after being approved as the sponsor. The email you get will either ask for more documents (this was our case), invite you for an interview or tell you your visa is ready.
They don't update your status online when Accra has received your file, you can just assume it was sent right away after you were approved as a sponsor.
I have a question for everyone though - does Accra acknowledge when they have received additional documents? We just sent in some police checks and hoping they will notify us soon that they have been received
Thanks!
Obrunicoco