Probably everyone has their own way of doing things that works best for them. When I do my laundry I like to get the water going first (hot or cold can be used) and then I toss in my bag of soapnuts, I add a teaspoon of hydrogen peroxide and some drops of essential oil. Then I close the lid and let the water run for a bit to get the suds forming. After about 30 seconds I add my dirty clothes and go read a book while the soapnuts do their business.
Simple, clean and eco-friendly. I also love to make soapnut detergent for washing my dishes, my fridge, floors, or even my vegetables in. How to do this can be found here