Make sure you have the money to build a house on the plot as well, as you're given I think 2 weeks max to build a house on the land before it is relinquished automatically.

Consider furnishing limits, particularly for outside, carefully; it's a lot easier indoors now but outdoor limit was not raised.

Furniture can be really expensive so if you don't craft but have friends that do, I would suggest asking for their help in getting your place decorated.

You can have tenants to share your house, and assign them permissions. If you give them permission to move furniture around, make sure you trust them, as they can most certainly steal items from you.

And most importantly, don't just get your house and ignore it! A lot of people would love to have a house, but it's a shame that so many get bought and then go unused beyond just resetting the demolition timer.

In regards to that, it's 45 days without entering, and it's demolished. It has to be YOU, the owner, not a tenant. You can check the status of your demolition timer under Estate in the timers tab, but they will also send you emails, and lots of them, if you are at risk of it being demolished.