What's a respectable time for 1 loop around Central Park Loop?

Where is the best starting point to begin a time trial? Where I usually enter is at a grade.

Here's a speed chart from the New York Cycle Club:
4-lap time Speed (mph)
1:10 or less 22+
1:10 to 1:13 21
1:13 to 1:16 20
1:16 to 1:20 19
1:20 to 1:25 18
1:25 to 1:30 17
1:30 to 1:38 16
1:38 to 1:48 15
1:48 to 2:00 14
2:00 to 2:14 13
2:14 to 2:30 12
2:30 to 2:50 11