Why the monthly based subscription for the DE Ticket!?

I don't get the monthly strict dates for the use of a DE ticket. I'm landing in Germany on the 29th of July for a month and will leave on the 29th of August.

I am planning to buy a DE ticket to travel in trains throughout the month and avoid paying a heck lot of money buying individual tickets.

As far as I've read, I can't activate my DE Ticket on the 29th July as soon as I arrive, or else it will expire on the 30th and wont work till the 29th of August, right?

That means I'll have to buy individual tickets to travel for 2 remaining days of July and only then will I be able to activate my DE ticket for it to remain valid till the end of August, which is also the end of my trip?

Please tell me this is wrong and that one DE ticket would be enough to cover travel from 29th July to 29th August😭

Dankeschön!