I load my wsm once with charcoal and 4-5 fist size chunks for a 16 hour cook. I like to place wood chunks around the ring in different spots as to optimze burn time. I also pour charcoal on top of a couple of chunks so they will go off later in the cook.
I have added wood towards the end of the cook just to make sure some is getting in there. On a 16 hour cook a burn the equivalence of 1-1/2 logs.
If you are not familiar with vertical smokers then there is a learning curve you will need to go thru just like I did. Everyone here will be glad to help you.