Fixed Gear Clone Question

I'm going to be brewing something similar to the Fixed Gear clone from Northern Brewer but I'll be using Briess Golden Light DME and it will just be a 2.5 gallon batch. My question is should I put in the DME at the start of the boil or wait till the last 15 minutes so I just sanitize it?

Fixed Gear Clone

Recipe

Extract/Grains:
3.75 lbs Briess Golden Light DME
0.375 lbs Briess Caramel 60L (Steep 20m/Until 170 degrees)
0.25 lbs Belgian Special B (Steep 20m/Until 170 degrees)

Hops:
0.5 oz Columbus (60 min)
0.25 oz Chinook (20 min)
0.5 oz Cascade (5 min)
0.5 oz Centennial Type (dry hop 7 days)
0.5 oz Chinook (dry hop 7 days)

Yeast:
6g US-05

I will also be cracking the specialty grains with a rolling pin so if anyone has tips for doing that, please give them.

I love that beer and have it on my short list and would also change it to DME and buy separately like you are. Usually I just do 50/50 on the late extract addition and would probably just do that in your case. You'd get a little more hop utilization so if you don't like that then consider reducing the bittering addition