Wanted to add 30 minutes minus on slider

[sagars12345]

Hello All,

I am having data and need to show in trend visual.

i have inserted one parameter slider from which if i select the pointer it shows hardcoded values present in visuals, for minus 30 min.

i have done grouping here eg if my timings are between 8:00:00,8:05:00,8:10:00 then it should be 8:30 like this

how can i make it dynamic.
for reference adding snapshot of data here.

Thanks & regards,