Once it reaches trace, the longer you wait, the thicker the soap will get. Getting to this stage can take hours, but usually happens sooner than this. After you achieve a good trace, you are ready to pour into your molds. If you leave the pot, for say 5-10 minutes and come back and see a layer of oil that has surfaced to the top, you need to wait and stir more, even though you thought you had achieved trace. This is false trace.
True trace is when all the oil and all the lye have reacted together and there is no separation.
The best time to pour into your mold is as soon as you can after your soap has reached true trace. Now you don't want to wait too long either, like past the custard looking stage, as you may end up with hardened soap in the pan. After you use the stick blender, you want to go back to hand stirring with the spoon so as to get the little bubbles out that the stick blender created. If you don't hand stir after using the stick blender, these little bubbles can become trapped as the soap begins to thicken. These little bubbles will be noticeable in your finished soap.