||Moses let his father-in-law depart, and he went away to his homeland.
Vayeshalach Moshe et-chotno vayelech lo el-artso.
In the third month after the Israelites left Egypt, on the first of the month, they came to the desert of Sinai.
Bachodesh hashlishi letset beney-Yisra'el me'erets Mitsrayim bayom hazeh ba'u midbar Sinay.
|he went away...|
See Numbers 10:29-32.
|first of the month|
(Shabbath 86b; Mekhilta; Targum Yonathan; Rashi; cf. Ibn Ezra). Literally, 'on that day.' This was the first of the Hebrew month of Sivan, around June.
|desert of Sinai|
This might have occurred before Jethro came; see Exodus 18:5. Alternatively, they may still have been in Rephidim, but since Jethro was coming from the east, he may have sent word to Moses when he arrived at 'God's Mountain.'