I usually leave the middle and top sections off for about 10 mins or so after dumping the lit coals on. Then I put them on and start w/ all vents open 100%. Sometimes I put the food on before I get total thin blue, but always not until the initial big white smoke has ended.
I have an easier time getting thin blue on my offset.
1/4" Cimarron offset & Webers galore. REAL men drink ALE.