You can try it, but being you already have the software (active or not), I doubt that trick will work. Additionally, remember you still have to have an Adobe account to even use the trial period. Since you already have an account, Adobe (it's servers) will already be aware of the products you have, so again, I doubt that trick will work.
Bottom line is You can try it and see what happens. Additionally you could call Adobe and ask them instead of having us opine here
Good luck.
Clearly it's outside the licence agreement, but that's not what you were asking.
Suppose you sign in machine 1 and 2 then take them offline. As you say, you should then be able to use them for 99 days on an annual licence.
You now try to sign in machine 3. It will say you can't as you have 2 already signed in, and it gives you the option to go to your account (online) and sign out one or more. Suppose you sign out machine 1 from machine 3. This should work. You don't need to have a machine online in order to sign it out from another machine. The next time machine 1 is online it will find it's been signed out.
This has worked for me. I have CC installed on three machines but have only 2 signed in at any one time. Sometimes a machine gets signed out from another machine while it's powered off, and that works. When powered on, my machines are almost invariably online, so I've never tried to use more than 2 CC copies at once.
However, if you try to sign out 3 machines without any of them being online, I wonder if the Adobe servers might smell a rat.
You can always try it, but remember that it's breaking your contract. If Adobe decide you're deliberately flouting their rules there is a (slight IMHO) risk that they may cancel your contract, as you've broken the terms.
