What is a normal age to have sex?
Naturally it is from the moment of puberty, when the body is able to reproduce from then on the body is at the normal time to have sex.
Why marriage at 30 years old?
if your not ready for marriage now.....why not?
do the answers you reply with not give you reason to abstain from intercourse?
again why 30, why put a time on it?
If you loved the person, you would want to marry them straight away...how do can you test if you love them or are merely infattuated.... a method that is used by many devout catholics is to remain in the relationship for two years without engaging in sexual pleasures if after two years the relationship is strong and a sense of love exists then it is a very good sign.
So if your 18 in a relationship wait 2 years without sex ect, if after 2 years everything is fine, then it is a good sign that Marriage would be successful. Once married then the couple need not try for a child but still are able to engage in intercourse without artifical contraception via natural family planning, that is intercourse planned around the fertiliity cycle.
Engaging in sex before marriage confuses the person since one of the purposes of sex is to build up a relationship that is already founded on love. It also means there is the possibility of getting pregnant outside of a commited relationship which leave both parties in a strange possition.
As a result my advice would be abstinance for 2 years then get married...and if you fail to remain chaste in that time end the relationship.... it is a method I use myself.