Planning My First Tri in June... Realistic?

Hello everyone, five weeks into my training and I am coming out from lurking.  I am shooting to complete my first triathlon in late June.  Currently I am thinking I'm going to attempt to complete an Olympic distance tri.  Is this too ambitious for a first timer?

Here's my background: I am somewhat overweight (5' 11", 240 lbs) and am hoping to use training for a tri to help me get in better shape.  I have never competed in a distance race in my life, but I am somewhat athletic.  I'm most comfortable with the bike section as I've commuted by bike for the past two years and mountain bike often in the spring and summer.  I am using the 16 Week Olympic- 2x Balanced plan as my training guide and have (and plan to continue) to keep to the training schedule. I added two weeks to the training by repeating weeks one and two.  So I am starting my fifth week of training but am really only on week three of the program. 

As of now, I can swim 1500 meters in about 45 minutes (with a couple breaks), I've run 4 miles in 44 minutes, and have biked 25 miles in 80 minutes.  I haven't done any of these consecutively. 

So, what do you think?  Is completing an Olympic triathlon this June doable?  And what time for each leg of the race should I be shooting for?

Thanks.