The Subnet Scan Status page will give you the status of the scans in queue, although it won't give you percentages.
I know that I can see the status of which subnets are being scanned at the moment and which ones are queued up and which ones are set to go at a certain time in the future. I've got 15 pages of subnets that are queued and 26 pages that are scheduled for the future. I would think that if it was completing all of my subnets in less than 4 hours, there would be less subnets queued up waiting to be scanned.
I guess I was just looking for something similar to what I could find in NPM where I can query the database and get the Polling Completion values or use the Polls Per Second Tuning application to tweak it if needed. I did find that after installing IPAM and letting it run for a week or so, that the Polls Per Second Tuning app, said that I needed to increase my values on the server that IPAM is installed on.