@Thomas, the second option what I also I was thinking. Although this will not give actual quart date but its somewhat close to it.

@Pavan, this will edit the dataset not the report right?

@Thomas Dodds, Thanks for the help. Actually I need quarter start and end date as default value for Date parameter which user can change using the Calendar. I can not go for DDL or List_Of_Values option as this way user will not be able to change dates as per his/her choice.