First night not always happens when guy is ready and wants it. It can happen whatever age. Their pluses and minuses have both – early and late beginning of sexual relationships. If boy is very young he might not be mentally ready for it (during masturbation he has built for himself a perfect image though his first real contact might not be close to perfect and might bring him disappointment and unpleasant feelings). Young boys seldom think how to protect from STD or his girlfriend from pregnancy. In early age boys can often have a problem of premature ejaculation.
Though at age 21-23 guy start to have inferiority complexes which create psychological problems to start relationships. Older guys often are having difficulties at their first contact – with premature ejaculation as well as with lack of erection.