If girth is what you want concentrate strictly on girth. You will still make gains in length because girth will effect this but you will mainly gan length. If you are going to a strictly jelqing routine you will want to use the exercise that gives the most expansion. I would start with basic jelqing and work your intensity up over a week or two. After you feel comfortable I would switch to the
SlowSquashJelq as this will bring girth fastest. You may also want to pick up a
Bathmate to use in these sessions. The combination of the
SSJ and the
Bathmate is amazing, expansion has never been so easy.