Swim Time Guestimate

I am signing up for my second triathlon and they want to know my estimate for the swim.  It is going to be a 300y pool swim.  I have never timed myself for this distance, but this is what I do know.  My first ows last weekend for the race was at 1:47 per 100 yards for 820yards (zig zagged and slowed for siting).  Last week I did some pool 100y intervals at 1:35 (6 of them, plus a 400 warm up before) and I wasnt pushing and could have kept going on them.  I want to seed myself right so that I dont deal with slower swimmers and I dont get in the way of others either.  I was thinking of submitting between 4m30sec and 5 minutes.  Does that sound about right?