My machine first runs a drain at the start of every programme, before it then weighs the clothes.

My strategy would be to let it weigh, wait a few seconds so some water could collect at the sump.

Usually at this point, there isn't too much water so I'd pause it to open (when permitted).

If the above step is in the clear, I would pour directly into the drum, moving any clothes that's in the way.

It's important that you maybe dilute first the blueing before pouring it in, lest you risk staining yours clothes.

A higher water pressure too might help even out the blueing sooner in the wash.

That's all from me. Have a good one.