Lot of questions about Masturbation in general so I'll go over points people keep asking about.
It takes as long as it takes to masturbate. There is no wrong or right duration. Keep yourself lubricated if you're masturbating more than a few minutes. I'd advise against KY jelly or other petroleum-based lubes, they're hell on your skin.
There is nothing about masturbating approximately once a day that should cause you to feel discomfort or feel ill, you should't see any noticable change to your ability to become or remain erect. If you are experiencing problems with normal masturbation see your doctor as there are likely other issues that need to be addressed.
Masturbation is the natural process by which boys learn to control erection and orgasm. The process of male masturbation strengthens the BC Kegels and helps a young man recognize the natural course of his orgasm. Normal masturbation helps men have and maintain erection, have more control over the duration of sex and increases orgasmic pleasure.
If you are concerned about short duration or performance anxiety don't abstain from masturbation. Abstaining makes the penis more sensitive and heightens sexual anxiety, making it hard to achieve erection and keep sexual stamina. Instead Masturbate a few hours prior to your date but stop short of orgasm. It will keep you at an elevated level of sexual need but frustrat your ability to reach orgasm, delaying how long you can perform without orgasm.
If there was soemthing else people had questions about that I didn't see allways feel free to IM me.