You have sex if you want to have sex and only when you are ready. You might not feel like having sex at all, or might even want to feel ready in your 20's, 30's or so forth. Some people feel that its the be all and end all and sleep with loads of people. Thats up to them. If you want to meet someone special first and dated for quite some time before you are ready.
Definitely dont put too much emphasis on the sex, but having a good time on the dates and getting to know a person. Then, when it becomes more serious, you can then at that point tackle the subject.