I have let 3 tenants out of their lease with what I consider proper notice, 60 days, enough time to have it immediately occupied.This has always been financially beneficial to me because rents have always been raised. 

There is a 60-day notice required on any lease changes.

I look for vacant properties when I'm driving around and noticed your house has seemed vacant for a while.

I noticed the property had been under contract recently and came back on the market.

I’m in the Seattle area and notice areas in FL appear to have more favorable ratios, but I’m not familiar with the area.  

When I gave them a 60 day notice they began looking for another rental. 

I have a clause in my lease that the lease renews automatically every year unless the tenant or I provide 60 day advanced notice in writing.

I know I should be doing more but I've noticed with every year I mature the easier it is for me to understand the concepts of different real estate strategies. 

I gave my tenant notice verbally and in writing 6 weeks in advance.

I got lucky on these two things with my first building but when I started doing my SFH I quickly realized I was going to have to upgrade systems and the heating bill was killing me and the more buildings I looked at the more I started noticing the discrepancies between the taxes and utilities between properties in the same town and in different towns.