How long does it take for it to work? Is it totally immediate since all you're doing is going to the bathroom before to do it?
Also, how much less painful is using a 31g as opposed to a 29g? I only have 29g and a little worried it could hurt a bit. I could order 31g but only if it really makes a difference
The first time I used Caverject, I was 37 years old and I used a 20mcg dose. It worked immediately and I could literally see my cock inflate to it's maximum size in a matter of seconds after injecting, just inject and then...boing, a huge hard-on that wouldn't go away for hours. That was a fun time and a very positive experience.
Now I'm 50 years old and a 20mcg dose of Caverject still gives me a great erection, but it takes a minute or two to get to it's full size. Which is fine, I inject, then apply pressure to the injection site with my finger if it is bleeding a little, and slowly my dick fills up with blood to it's maximum size. I just stuff it back in my pants, zip up, and go back out to start kissing my girl and foreplay and all that, and by the time we are ready for sex my cock is completely hard and ready to go.
29g needles aren't really much more painful than 31g, you can definitely get by with 29g if you want. The main reason I prefer the smaller 31g pins is so there is as little scar tissue as necessary. I have been doing this a long time, and I intend to keep on doing it for a very long time, so I want to make sure I have as little scar tissue as possible so that my cock will be healthy for years to come.
The same is true for steroid injections. When I started using steroids 26 years ago, everybody used 22g or 23g needles. Now I prefer to use 25g or 27g 5/8" pins for steroids injections. Why risk more scar tissue unless you need to? But you can always get by with a bigger gauge if you have to.