[Landlord-US-TX] How much of a notice is appropriate to give month-to-month tenants a notice for an increase in rent?

My wife and I are about to become first-time investment property owners, and the property we are about to purchase currently has tenants renting on a month-to-month basis. Once we take over, we plan on implementing a new lease agreement with, as you may have guessed, an increase in the rent.

The current tenants are on a short term lease agreement due to them expressing a desire to purchase their own property somewhere nearby, and did not want to be in another one year lease if they found something that would work for them.

My question is this, once we take ownership of the property, we plan on immediately expressing our desire to go back to a yearly lease, as well as increased rent for the property. We are willing to give them time to decide whether they want to stay or go (these tenants are actually relatives), but how much time is an appropriate amount to give? Also, I’m guessing there are laws as to a minimum time frame required in giving a notice like that, but does anyone typically go further than the allotted time?