Visitor visa for my mom

[may08]

Hi
I am a housewife so my husband is sponsoring tourist visa for my mom. I am expecting, my due date would be in may, my mom wants to come here by first week of may 2008, i am planning to get appointment for the visa interview during last week of novemeber 2007. My question is

If she gets 6 months visa, the 6 months is calculated from the next day of visa issuance. or the 6 months validity is calculated from the day she enters U.S.
please help. Thank you.

[PraetorianXI]

The validity of the visa starts the date that the visa is issued.

[may08]

thank you.