How soon can you begin to experience pregnancy symptoms?

So I had really nice EWCM Friday (CD 14) and it is now Tuesday (CD 17) and my are extremely sore. I've never experienced tenderness during ovulation so I'm not thinking it is from that (although it is always possible). I got a - OPK on CD 14 when I had the EWCM but I know I HAD to be ovulating so we BD that night. I got + OPK the next day but nothing else after that. When I got pregnant 5 years ago my were extremely sore and that's how I knew I was pregnant. Anyway, is it possible to be experiencing pregnancy symptoms at 4 dpo? I'm trying not to get my hopes up but this is my 3rd round of Clomid and I am very much hoping that I won't need another round. Thanks for the help, ladies and baby dust to all in TTC land!