Programmatically trigger app update from Google play

Question

1. Once an update to app is submitted in Google play developer console and the app is visible to all users, how much time would it take for any device to pick the update?

Answer 1

1. It depends on Google's back end replicating your new update, usually within 8-24 hours.
2. No, that would be a security vulnerability. Apps are not permitted to install or update themselves without user interaction.