Timing of new Xfinity Mobile promotional line purchase and activation

I signed up for the $50/5 year Gig internet plan on January 4th. I see the following terms regarding the free year of an Unlimited Xfinity Mobile line:

"You are eligible to receive an included Xfinity Mobile Unlimited line for $0.00 for 1 year. To claim this included line, you must purchase Xfinity Mobile within 90 days, and the Unlimited line must be activated within 1 year of purchase of Xfinity Mobile."

Does this mean that as long as I purchase the line within 90 days, I can wait to activate it until June?

If I purchased the line on April 1st, for instance, what would I be responsible for paying at that time? Would I need to pay anything else until the line is activated?

If I then activated this line in June, would I receive 12 free months of service beginning in June?

Thank you for your time.