Jon mentioned in the discord
the 3 years will begin from the purchase date of the bundled license, the system isn’t smart enough to do any sort of pro-rata incorporating remaining time on the upgraded-from license key(edited)
but the bundle price isn’t discounted, and will remain at the current price in the future
when your SM license is >3 years old, you’ll be able to upgrade it, and bundle ST with it at that point if desired
The general idea being that in essence they’re always synced when you bundle because you start a “fresh” 3 year license period when you do it.