Found a solution for this. In case of a private-channel you can use slack inbuilt /remind command in following way:
/remind @channel every weekday at 2pm to start daily standup.
Here you can use either @here (to remind only online people) or @channel (remind everyone in the channel irrespective they are online).
This was a nifty trick I used with my private slack channel. Wont find it on slack documentation but it works.