I'm a guy and I currently have a 4 months old male Boxer. I'm not sure when I can start teaching him to mount me and when it's safe to start, any help?
Oral sex it more or less about masturbating a male dog with the added benefit that in the end you do the masturbation with your mouth. So lets begin with how to masturbate a dog. Castration/neutering: The purpose of castration is the removal of sexual behavior. "Another benefit of castration is...
2. "When Do Puppies Reach Sexual Maturity?
"The timing of sexual maturity is largely size- and breed-dependent. So, talk to your vet and breeder about your puppy. Sexual maturity in puppies typically begins to occur between 6-to-9 months of age, although certain giant breeds may not reach sexual maturity until they are older."
(https://www.akc.org/expert-advice/health/sexual-maturity-in-puppies-what-to-expect/)
Generally speaking you should not attempt to masturbate a dog until he is sexually mature. You should wait for the dog to show sexual behavior like interest in female dogs and mounting/humping.
By the age and situation.
A god sniffing and trying to mount a female dog in a sexual manner will be quite easy to recognize compared to a puppy playing.
You will meet dozens of them in the streets. And especially if you attend some group dog walks/school/socialization sessions...
Which you should with a puppy.