Do you receive the fullness of the Holy Spirit the moment you get saved?
Yes. At salvation a believer is filled to the brim with the Holy Spirit and has all of God that can be placed within them. This fullness is received the moment one believes; it is not earned or sought, because it is part of salvation. Believers may later choose how much fullness they maintain.
Les teaches that the moment we are saved, we have all of God as He can put Himself into us. We have everything regarding the fullness of the Holy Spirit from the very moment we believe. You do not have to work for it or look for it; that was all part of salvation. However, God leaves within our realm of control how much of the fullness we maintain, or whether we let it empty out. Les uses a cup analogy: a cup full of liquid must have liquid poured out to be filled with air. The Holy Spirit is likened to air, or pneuma. The moment we are saved, we are filled to the brim with the Holy Spirit. A newly saved person may be bubbling over and excited. But in the world with its allurements, temptations, and fleshly desires, we may start filling the cup with material things, so that eventually the cup is full of the material instead of the Holy Spirit.