Hey mate and welcome to Thunders place. As they said before gains are pretty much completely random. On average people will gain about .2 inches in the first month. However I would say it is more common to gain more in your second month. This is because the most important thing is to find out what kind of routine works best for you. Are you a guy that will gain more from lot of weak strokes or more from less, harder strokes held for a longer time. For me I gained maybe .1 of an inch in the first month. I was jelqing way too hard. I found a thread on PI which you should defiantly read and I realised I wasn’t giving my member enough rest time and working it too hard as well as uping my routine too quickly. So I switched to lighter jelqing for a shorter period of time and gained about .25 in the next month. For some people however, working the hell of there cock is better for them. If this is you your still going to have to work up to it. Figuring out your best routine is key.
A few tips are jelqing is a lot about the continuous light stretching of the internal structure, not about trying to inflate it like a balling until it’s about to burst, or else like a balloon your member will be rather deflated for a time.
DO NOT OVER WORK. Patience is so important, you WILL cause an injury and if you don’t you still will inhibit gains. So make sure you take it slow.
Consistency is extremely important as is rest days.
If your looking for quick gains stretching can be very important, especially if your LOT is high (this has been slightly discredited but it probably does mean a little). Stretching is also far less intense on your member so you can do it more often with out worrying about over doing it.
Lastly don’t be discouraged if you don’t gain right away. If you PE, you WILL get a larger cock.
Best of luck mate hope this helped.