Hi Tracy,
I don't know how long a Jr. Olympic pool is! My first tri this year is a pool swim, .26 mi or 450 yd. That's 16 lengths in a 25m pool, or 20 lengths in a 20m pool. I did the math, because I train in a 20m pool, but race in a 25m pool.
Yours will be an ocean swim? Out and back, or parallel to the shore, or what? I always find it helpful to see the distance I'll be swimming, and walk it out along the shore if it's still too cold to get in the water.
You've got until July, and you will definitely be well enough trained for that distance if you start swimming now. If you get comfortable swimming 1.5 times the race distance, you'll cruise on race day.
Good luck, Lise