I became Plat more than a month prior to the official merger - took no chances even though I could earn through the end of the year, in theory.
As a first time Plat:
Earned one Delta crossover reward on SPG stay
Earned a suite upgrade at check-in the day before the official merger. My only stay after becoming a Play prior to the merger.
Now I am off to Hilton.
Completed 5 of 8 stays through it's Diamond challenge. Upgraded each time.