This question has been asked numerous times as if somehow the answer is going to change.
You are a singular and unique individual. Some individuals will respond over time to vacuum, but will not respond to manual manipulation techniques, some will respond to manual manipulation techniques and will not respond to vacuum.
In my own case, I have been able to increase girth through vacuum, but I have had very poor experiences increasing length through any method I have yet tried.
The main thing is to take it slow, devise a routine and then stick to that routine as if it were a part of your employment. It will take a minimum of six months to absolutely and positively be certain that something is or is not going to work for you. This is not instant gratification by any means.
A great deal will also depend on the strength of your own ligament structure (length) and your age. The younger you are the greater the chance is that your ligaments structure may still have some give in it.
The most important thing is that you do not give-up or lose the ambition to continue on. This is one where patience and persistence pays.
Good Luck.....