How long is ideal for a courtship to last before marriage?
This is a one of a kind question but in my experience, it doesn't really matter. You can married anytime as long as both of you would agree and are on the same level of feelings.
I've been married for 4 years, my daughter is also 4 years old but the time me and my wife have been in a relationship or courtship was less than 6 months.
To some it may be fast but for us, it was just the perfect timing because we know we're at the right age, both have decent jobs and truly love another.
And here we are, happy being together along with our daughter and our family, that amount of happiness can't be beaten.
So don't think of what others might say, if you and your partner agree and are both ready for it, go ahead and get married, it's a one of a kind experience.