You`re better off to give it a shampoo / wash to remove factory-residue,especially silicones which can prevent a good bond. It will also help to `dull` the hair a bit which is very shiny from the silicone....also removes some of the `excess` colour in the case of darker hair. Give your system a few gentle brushings over the next few days and mist with water..this all helps to `relax`the hair and take some of the bounce out of it....makes for a more accurate cut-in in my opinion/experience... a system brand new is quite `lively`..if you get it cut-in immediately, it can look different/need further `attention` [trimming] a short time later ...systems need time to settle-in...when you first see a system it can be a bit `scary`..you can wonder how will this ever look ok on me.... if you follow the steps above, and then go for your cut-in, it`ll be ok. Cheers.