Sforno on Numbers 11:35/ספורנו על במדבר י״א:ל״ה

1ויהיו בחצרות. They remained there for a period the length of which has not been revealed. We find this expression, for instance in Ruth 1,4 where the period is defined as about 10 years. In Deuteronomy 10,5 when Moses speaks about the Tablets remaining in the ark in which he deposited them, the period was considerably longer. In our situation it is reasonable to assume that the length of time meant is the period during which Miriam had to remain in isolation. Seeing that the Tabernacle had already been erected by that time, G’d invited all three of them to leave their tents and to come to the entrance of the Tabernacle.