I have read through that state of WI at will tenancy termination laws:
Here

However I still have a question. Mainly,

I am closing on a property within the city of Milwaukee May 6th. I am doing an owner occupied and I am required to move in within 60 days of closing. All units are rented, with the earliest lease ending April 1st and going month to month May 1st. The seller did not want to give the tenants notice in case the deal falls through.

So, I see two possibilities here. I would like some advice on if the first one is legal (or a proper resource you guys may have for that).

Option 1:
Upon closing, May 6th, I give the tenants a 28 day notice to vacate ending June 2nd. The two day period of June I dont prorate rent, or charge them at all. 
The issue is I think the notice has to end on the last day of their rent period. Since they pay on the first.

This leads to option 2:
Give notice on May 6th (or maybe June 2nd after I get the rent) to vacate July 1st.

I know option 2 is legal. What do you guys think about option 1? I am giving them the full amount of time to vacate, but looking at the tenant's perspective, how would they find a lease starting June 3rd? They would almost need a lease starting June 1st and... effectively moving out May 31st.

Thanks!