“On the third new moon after the Israelites had gone out of the land of Egypt, on that very day they came into the wilderness of Sinai. They had journeyed from Rephidim, entered the wilderness of Sinai, and camped in the wilderness. Israel camped there in front of the mountain.”
In about 3 months or 90 days they arrived at the foot of Mount Sinai. There they camped facing the mountain. This is the holy mountain where all the good stuff happens.
Eugene Finnegan Bible Project 