EAD file in local office??

the local office said I should mail the 130, 485 and EAD application together, but I am having a baby, can't work in the next six month, should I wait then to file my EAD?
the Local office only accept package by mail, does it mean that might have to take 3 monthes to process my EAD or might be like others to get it in next few days?
After I receive my EAD, if I didn't start working right the way, would it still start counting time since the day I receive?
thanks for any kindly reply