You'd be best off doing a search on the subject and then asking any additional questions that have not been covered. There is a ton of information in the archives on this subject.
depends on where your racing, what tires your running, what time of year it is, if your running up front, or in the back of the pack. for instance, if its 100 degrees out, and your racing on a track like jennings gp (lots of grippy pavement), and your not competing for 1st place then you really dont need them from that standpoint. but if your racing at loudon in sept, you will want to use them. im kind of making light of the subject here. they are always important.. they will extend your tire life three fold. as far as performance goes... well, they only help you on the first lap. after that most tires are warm anyway (at a reasonable time of year). once you have used a pair you will never go back though.. it is a nice feeling knowing your tires are sticky when going into t1 on the start.
Track time is the most important now warmers are nice just the really help in knowing your tires are warm and should grip right out of the gate. Getting to know the bike on the track is going to be the main thing now. Learning the turns is easier if you know your tires are hot. But take your time for afew laps looking for brake markers and things you do not want to hit for a few laps will warm your tires too.
