Corn Sugar

I am making an Imperial IPA and was planning on using a pound or so of corn sugar to try and dry things out a bit. Here is the Grain Bill:
14.5# 2-row
2# Crytal 40
1# CaraPils
1# Corn Sugar

My question is when to add the corn sugar. I have read people adding it during fermentation just after the krausen falls. Is this best in order to wake the yeasties back up and start again... if so, do you shake them back into suspension, or aerate it again? please advise...

I'd add it in the last 10 minutes of the boil...

I would modify the 2#s of crystal and 1# of Carapils you have before even thinking about sugar. Cut them both in half, at least. If you want a dry beer - 3 pounds of dextrinous malts are going to do nothing but hurt you.