Someone can convey their desire to receive/give sex of any kind, but ultimately it is still YOUR decision to say yes or no, and nobody should make you feel bad for either choice you make.
When giving oral sex on a penis, done use your jaw to apply pressure, your jaw will get sore! You’ll want your lips/mouth around the penis, but you should use your hands to lightly squeeze/rub the shaft of the penis. The trick is trying to do both simultaneously.
Just take it slow and don’t force it to far or too fast.
Communication with your partner is important though, it may seem embarrassing, but don’t be afraid to take things slow and get yourself ready for sex. It’s better than forcing it and have it be painful.
It’s also important set boundaries before you engage in sexual activity. There have been times during normal sex that my girlfriend as told me to stop midway because she has experienced pain/discomfort. Sometimes it happens.
As to when you should start having sex, same as before, entirely up to when YOU feel comfortable and want to start having sex. Never let anyone tell you that a certain amount of time equates to the beginning of sexual activity, some people don’t wait at all, some wait months, even years. Everybody is different!
Guys get erect from kissing, hugging, talking, looking at thing, thinking about things, or even just by doing nothing. Especially younger men. If the guy finds something attractive, or thinks something feels good, chances are he can get hard. It’s all a case by case situation!
Overall, I would say that before you jump straight into sexual encounters with other people, you take the time to learn yourself and your body. It’s much easier to communicate and get yourself comfortable for sex when you have an idea of what your body responds well to, and what you enjoy.
Just please educate yourself on safe sex practices, and PLEASE PLEASE PLEASE remember that YOU are in control of your body, only do whatever you’re comfortable and happy with!
Best of luck, and hope this helped! (: