I encourage everyone who wants to start dating to immediately go for the D’or Yeshorim test if they have not already done it in school. That is step #1. Take the card they give you and put it with your important things like birth certificate, social security card etc. When you need it you will have it.
I don’t believe in checking before dating, nor do I believe in checking till after the 3rd date. If you are ready to go on a 4th date that is the time to check because your hearts are not yet involved yet there is enough interest to see whether you should continue. Doing so too early on will just be a discouraging situation for all, add tension and basically is for naught. Many shiduchim don’t go past the 4th date, so checking before a second date is a waste of anxiety.