I did mine.Dry fit as close as you can before applying glue. Error on the side of being too large as opposed to being too short you can always trim a little smaller if need be with the final fit,and glue down.
Don't make the mistake I made and use a closed loop indoor outdoor house hold carpet. If you do every hook that comes in contact with the carpet will have to be cut out. Use open loop marine carpet.
I'm doing it now too along with my wood. As said use look at some websites to read about installation, use a marine carpet and an adhesive that is compatible. My biggest problem right now is I'm doing it outdoors and the adhesive is temperature sensitive and not water resistant for 5 days.
Sorry I can't say I remember, it was back in the late 80's early 90's, and I was working on a 18.5 ft john boat that I had installed a floor in, the floor carpet was installed before the console or the rod boxes were installed,so no cutting or fitting there. The front and rear decks did take some fitting.Have never had to re-carpet the thing ,but it is kept indoors.