After medicals, if the officer is satisfied with your app, the next step should be SA, AIP, DM and CoPR but if they ain’t satisfied then expect more requests like PCC, proof of cohabitation or proof of relationship, CV and many more until they are satisfied then SA, AIP, DM and CoPR.
no specific timeline as every app is different and it also depends on the officer in charge of the app.
SA - Sponsor Approval
AIP - Approval in principle
DM - Decision made
CoPR - Confirmation of Permanent Residence.
others
PCC - Police Clearance Certificate.