As post 119 points out --
Sunday at 2:30 PM #119
In the NT it meant everyone assembling at a "place of prayer" Acts 16 or in the synagogues Acts 13, Acts 17, Acts 18.
And in Canaan when everyone was dispersed people did come together for solemn assembly on Passover etc and could involve days of travel to do it.
But in the wilderness where everyone WAS already assembled around the "Tent of meeting"
by the millions then they had a special case.
NASB
2 “Speak to the sons of Israel and say to them, ‘The Lord’s appointed times which you shall proclaim as
holy convocations—My appointed times are these:
3 ‘For six days work may be done, but on the seventh day there is a Sabbath of complete rest, a
holy convocation. You shall not do any work; it is a
Sabbath to the Lord in all your dwellings.
NIV
2 “Speak to the Israelites and say to them: ‘These are my appointed festivals, the appointed festivals of the Lord, which you are to proclaim as
sacred assemblies.
The Sabbath
3 “‘There are six days when you may work, but the seventh day is a day of sabbath rest, a day of
sacred assembly. You are not to do any work; wherever you live, it is a sabbath to the Lord.