Excellent stuff man, i had the same problem when i got my first kilt, i found that i was wearing it too low and after i hiked it up and it sat easier on my waist, my belt seemed to do it's proper job. Another factor can be how much you keep in your sporran, being a bigger guy i always wear my sporran strap through the loops, i've seen slimmer fellas wear it just around the wasitline without the loops, i've noticed that the heavier my sporran gets, the more it pulls, pretty abvious though... Theres nothing like the anticipation of recieving your uniform, i myself am waiting to get my uniform for the pipe band i am playing in. Congrats on the first gig, and many more!