I believe the best strategy for getting in line for Firehawk is getting there early and then running a full-on sprint. Although KI strongly discourages running in the park, my friend and I went at about 8:30 to get in line for the extra close gold pass entrance, and when they opened the park, sprinted from the candy store on International Street to the entrance for Firehawk. It was fun to be in line for the first train, and see a line that went from Firehawk, all the way to The Racer.
I'll be there tomorrow (6/22) and I'll check out the lines for ya.
Matt