As a second year u19 I think I can still (vaguely remember what u17 sprinting was like). In the juniors in a lot of cases the strongest sprint will also be right up there climbing tt etc. Just look at Leigh Howard this year at nationals. 2.23 pursuit, 200m national record. Also apparently decent on the road. The main thing is to be around people like him when the kick comes. You can afford to be a little bit in front but never more than two spots behind at state level as realistically the depth isnt really there. The same 3 or 4 will always place. In juniors everyone leavs it really late, rarely does anyone go before 300 to go because of the gearing. You've got two options there, hit them between say 2k and 400 metres out for the surprise effect or simply to be ready for it within the last 350 odd.
If your in front back off the person in front even if theyre good, (back off more for shit rider ie 10 metres, hardly aything for good ie 2m) and start lookingback constantly. By leaving the gap you lose the risk of running up someone while looking behind and also give yourself a much greater speed when you get next to them if you jump first. When loking behind as soon as someone gets out of the seat wind it up (have a quick look when ur winding it up just to make sure they havent foxed you), if theyre going faster at least you'll be able to get either there wheel or the persons behind. Dont be afraid to throw yourself around if you're confident enough.
Best thing you could do is start riding track if you dont already. If nothing more it'll improve your handly skills which will be usefull when you move up into u19. I think theyve got a winter series starting again soon for you guys.
I'll second what zakeen said about the 10 second sprints. My coach was the TIS head coach about 7 years ago and he has me doing these a fair bit. This month Ive only got one session on the ergo with 15 min warm up , 5x10 sec sprints with 2 min in between (might pay for more recovery as zakeen said) and ten min cool down. Have found that these seem to help with recovery when people attack during races as well. In your case I'd definitely do it on the ergo if youve got access to one simply so that you can find a good gear. want something bigger than u17 but not too much.
http://www.licoricegallery.com/features ... indoor.htm
short sprint sessions in the bottom left might be of interest for your leg speed and tolerance. Brought to you by the coach that took over from my coach.
Sorry that I rambled so much but I like my sprints. If you need anything cleared up give us a yell. Main thing to remember is that if soemthings not working after a couple of goes, try something else. It might take 5 years but one day everything will just click and you'll wonder why it was so hard before.