I left it there for 20-30 minutes continuously stirring every about 5 minutes to make sure the color develops evenly. This was my first attempt and it ended up making the duvet to light colored and almost gave off a pinkish hue.
You can try adding the yellow and tan in right away without dying it two separate times like i did. Although I should mention I do like dying it a little at a time rather then adding too much color all at once. Better safe then sorry. Sometimes if you add too much tie die and try and add a darker color too fast it comes out spotty.
Once you achieve the color you like a simple wash cycle in the wash machine with some white vinegar should help lock the color in. I didn’t add any detergent to the wash cycle. Just warm water with about 1/2 cup of vinegar. Then dried it in the dryer. The heat from the dryer helps lock in the color even more.