This paper presented the optimal operation strategy of Fast- SAGD(Steam Assisted Gravity Drainage) process considering steam channeling among vapor chambers. To accomplish minimum cSOR(cumulative Steam to Oil Ratio), it was energetically efficient to start CSS(Cyclic Steam Stimulation) using the wedge well after the steam chambers of SAGD crossed over each other. The early start-up of CSS operation caused steam intrusion into the SAGD chamber that imposed the minimum operation of SAGD. When the SAGD's chambers expanded sufficiently, the mature pattern of steam chambers decreased the production efficiency dramatically. High injection pressure of CSS can make more efficient production by blocking unnecessary steam injection from SAGD and pushing latent bitumen to the SAGD well pair. After steam chamber of wedge well grows enough, it had better to maintain the low steam injection pressure of the wedge well to use the latent heat of the reservoir.