Using Presentation Variable in timestampadd function

1) Create a prompt day week and declare presentation variable

To show 30days back booked quantity the date selected in prompts

In fx use

FILTER("Facts Other"."Booked Qty" USING (Time."Day Date"=TIMESTAMPADD(SQL_TSI_DAY, -30, DATE '@{day}')))

You can apply the same formula for 1....n days

For month level use
FILTER("Facts Other"."Booked Qty" USING (Time."Day Date"=TIMESTAMPADD(SQL_TSI_MONTH, -3, DATE '@{month}')))

where -3= three months back