Why Power BI Services late to start refresh?

HI Anonymous 

When you schedule a refresh in Power BI Service, that refresh request enters a queue and may wait in the queue for up to an hour before being picked up and run. This is Microsoft managing the load on the Power BI servers which are used by all the Power BI community. Manual refreshes are not queued but run straight away, so they appear to take less time.

So this is why an Automated Refresh may appear to take longer as it spends more time in the queue waiting to run.

If the time taken to refresh is important to you, you may be able to shorten the queue wait by scheduling a refresh outside of busy business times. Scheduled refreshes at 9:00PM are often quicker than those at 9:00AM.

Aside from that, there's not much else you can do apart from using a Premium Capacity or Premium Per User licence. The Premium licences run on dedicated capacity, so don't need to share with the rest of the community, hence queue times can be much shorter.

Hope this helps

Stuart