Dear Teacher,
Further reference to my vacation for the year 2007, I would like to inform you that I am planning to leave for India on 25/03/2007.
Kindly arrange the Air Ticket and pay Vacation Salary at the earliest.
Regards,
Sneha
Further reference to my vacation for the year 2007,- unclear; have you written before? If so, I'd say 'Further to my ealier letter about my vacation...
at the earliest- at your earliest convenience