Add template variable for start time

Hello
Help me please, i have this issue and cant find way to solve it:
in deadman alert i need add time, when problem was detect. For example i have similar tickscript:
====
var data = stream
|from()
.database('telegraf')
.retentionPolicy('autogen')
.measurement('values')
|window()
.period(10s)
.every(10s)

data
|deadman(0.0, 10s)
.id('task `{{.TaskName}}`')
.message('''[{{.Level}}] Postbacks data is missing timeframe: *10s*, value: *{{ index .Fields }}*''')
.log('/var/log/kapacitor/mem_heartbeat_stream.log')
.slack()
=====

this script work fine and make alerts is log file. But i need add time, when problem was begin. I mean that in first time alert should be next:
"message('''[CRITICAL]. Postbacks data is missing timeframe: *10s*, value: *0*''')"
the second time alert:
"message('''[CRITICAL]. Postbacks data is missing timeframe: *20s*, value: *0*''')"
third time:
"message('''[CRITICAL]. Postbacks data is missing timeframe: *30s*, value: *0*''')"
etc.

but in every alert there is *10s* value

if its possible, explain please how to make this

Thanks

Start with the deadman alert entry point and the template variables used by the shown TICKscript. Determine how alert state and elapsed time are represented across repeated alerts, then define the expected start-time variable and verify that the example messages expose increasing durations. No source file or test is named in the issue.

Written by the indexing model from the issue text.