Having sex is a big leap in any relationship and should be taken very seriously by both partners. Both should be prepared for whatever consequences and be honest with each other regarding your sexual pasts.
Some people might not be bothered at all even if you've had quite a number of past experiences, while some might be put off by your previous conquests and act differently. But an important thing to remember when talking about your sexual pasts is not to be judgmental and let go of the past by moving forward with your partner. You shouldn't hold a person accountable for something they did before you even met, and to focus on that will only lead to fighting. It's best to leave the past behind, as you or your partner can't change it and move forward towards the future together.