Yes, you can use the software offline. That's what it's designed for. There's no set date for checks. The activation check is sophisticated and flexible. Depends on when it last detected an active internet connection on your machine. On an annual plan, billed monthly you can go up to one calendar month+99 days without one (30 days on a monthly plan, billed monthly).
For full detail, see Internet connectivity, offline grace period, and reminders | Adobe Creative Cloud apps
See also Need to work offline?
Creative Cloud activation and sign-in troubleshooting
It's good practice (but not crucial) to sign in with an internet connection for an activation check just before you leave. That'll give you a 99 day reset.