It is ok to add part of the tabs when you drop the bean, but unless you are transplanting, it is best to wait until week two or three, and slide them down on the sides of the plants being careful not to break roots.
I added P heavy guano and two tabs I never my fifteen liter pots when the beans went down, then added another tab at week three, then fed the orgatrex heavy at week five and then top dressed with Silicium Flash at week seven.
The tip burn would be from the tabs maybe not being buried deep enough , or sometimes if you overwater a bit, they break down too fast and that's can cause that. I like to push them until a little tip burn myself, then I know to dial it back a touch with feedings and go from there. Then you are sure to get max yield.
You do NOT want to be pushing Biotabs down through the soil and roots one or two weeks into the grow. Do not do this if it can be avoided. And if can be avoided so don’t do it.
Auto’s roots are super important and are massively important in the final yield. You only get one chance with autos. Don’t fuck with the roots.
Tabs in then plants in. Whatever method you use.