If the duration of the period is not specified, it is assumed to last the minimal number of 30 Days: Moed Katan 19b; Nedarim 4b
The minimum period of being a nazir: Bechorot 12b
If someone takes a vow to be a nazir but doesn't observe it at first, do those original days of nezirut count toward the period of nezirut?: Nazir 32a
If someone takes a vow to be a nazir but doesn't observe it, then asks a sage to repeal the vow, and the sage upholds the vow, do the original days of nezirut count toward the period of nezirut?: Nazir 31b, 32a
