Đó là tốt nhất thời gian, đó là tết nhất thời gian...
I was going for: It was the best of time(s), it was the worst of time(s). First line of the Tale of Two Cities.
Là thời gian tốt nhất, là thời gian tệ nhất. You can also omit "gian". Furthermore you can replace tốt (good) with đẹp (beautiful) and tệ (bad) with xấu (ugly).
may I stress on the fact that VNmese adjectives come after the words they modify most of the time.