Transitioning existing members over to paid subscriptions

I would be grateful for assistance in setting up existing members for annual subscription. The anniversary dates vary and there appears to be no way to set the start date of each subscription so they are billed/notified at the correct time.

I suggest using the import feature for that. You'll be able supply a start date in your import file. Suggest reading the CBSubs Manual which you can download below regarding the import feature in CBSubs.

www.joomlapolis.com/downloads/documents

For your specific case within CBSubs > Import you'll want to use file based importing so you'll need to set "import users from" to "File (each line: userid,planid,status,subscription date)". Now you can create a text file with your imports as follows.

42,30,A,2022-02-18 00:00:00
43,30,A,2022-01-10 00:00:00
44,30,A,2021-10-01 00:00:00

The above would import a subscription for users 42, 43, and 44 with a status of Active to the plan with an id of 30. It would give them each different subscription dates.