I only read the first page of this thread (I display 50 posts per page), but judging from the information you gave in your first page posts, I don't think you are ready to have sex with this man, yet. Forcing yourself because it is expected or you think you need to appease him is probably not the best way to get this going. If he can't give you the time you need, then you need to question the nature of his feelings for you.
As for the question you ask, there is no set time. Each person is different, each relationship is different. "Third date", "fourth date" "four months" these are all stereotypes and social norms that do not and should not apply to everybody.
Do it when if feels right for you, regardless of the timeline.
And yes, do look for lab tests. many STDs can be silent; the most concerning of them all, HIV, will have virtually no symptoms for months and years, in most cases.