I believe this topic has been brought up before, but I will post the same video I have posted before on this thread:
It's been a while since I listened to this talk, but as far as your questions go, the whole process from Date number 1 till marriage should be 1 year. Ideally, you get to know the woman in 3-6 months, get engaged in month 6 and get married 6 months later. As you pointed out, it is difficult to stay chaste with a woman, especially if this is an area you have struggled with in the past. However, if you take precautions, are virtuous and are serious about meeting a woman who will be ideal for marriage, you should be able to hold out for 1 year. The key to this is not being near the occasion of sin, ie "netflix and chilling" in each others house alone, being alone for extended periods of time outside of the home, passionate kissing, etc. Seeing how most of us used to be fornicators, I think we all know what leads to fornication...so don't do those things. The maximum amount of time should be 2 years. If you are not married by year 2, leave. This is true whether it's a Christian courtship or secular dating.