is there a time to discuss marriage

i had a chat with someone and he goes like am dating and we havn't  talk about when we are going to get married so i asked when is the right time to discuss marriage between two people who are dating and are acquainted with each other.the main question we should ask is how do we start the conversation about marriage how to go about it.when is the right time to talk about it,is there a place or time it should be discussed.who should start such discussion is it the man or woman.and what do u talk about when it comes to discussing marriage.