The blastocyst continues the trip down the Fallopian tube and reaches the uterus about
days after fertilization.

5 to 6 days

Explanation:

Fertilization usually happens in the part of the fallopian tube that is closest to the ovary and the embryo continues to develop (through cell division) as it travels back down the tube towards the uterus. The embryo usually reaches the uterine cavity about 5 or 6 days after fertilization.

You should only go in for less than 10 minutes at a time, or avoid them altogether, especially in the early weeks. studies have shown an increased risk for birth defects in babies of women who had an elevated temperature before 7 weeks of  pregnancy.