My Personal feedback on Blinkit. Have ordered in Bangalore and Chennai in last few weeks. Out of 5 times I ordered, once the delivery time was 16 min , rest others it’s 23,23,26,29 min. The app says the order is packed in 3-4mins and then there is a big delay in assigning delivery agent. Had I seen this just in one place I visited, I would have thought may be it’s a busy locality. Since I saw the same in a different city , I feel they are not having enough delivery agents at least in the localities I stayed. Also the location I stayed had BB Now which delivered the goods in 6 min. So I ended up using BBNow multiple times because of Blinkits delayed delivery time. I think they may need to may need to manage the number of delivery agents better to stay true to their 10 Min delivery tag line.
My only concern was me being invested despite my personal urge to order from Blink had to resort to BBNow more than Blinkit. 
The others might do too the same if the delivery times are higher.
Hope it gets better with time.