When Dashboard data is being refreshed?

Connections and Sessions are simple additive counts over days. These metrics are updated every hour.  

Impressions are also simple additive counts usually refreshed every hour, but a processing latency may occur. 

Some metrics like Reach or Estimated earnings are based on more complicated calculations, instead of simply adding (or subtracting) processed data from the pre-aggregated tables. The processing latency for these metrics is at least 24 hours.

Please be aware that default date range is set to "Last 30 days". That may be the reason why you can be confused. If you want to see today's data, just select a current day in a date picker.