depends on how long and/or short your waist is ;-)
....adjust them to where they are suppose to be in relation to your size.....then trim them if you want. i trimmed mine when i got my buckles installed......i think it was about 1.5" of tail past the buckle or so.....could be more...
It depends on the hardware and how you place the straps on the jacket. If you have D-rings or rectagular rings and double them back then you lose a bit of that length, making them the correct length. If you do the 7-8.75" on a Todds with a roller or single strap it will be too long. Perhaps 5" will do.