What is the best way to go from Yichang to HKIA to transfer to Malaysia? Shenzhen or Guangzhou?

I will be finishing a China tour on 11/8 at Yichang late afternoon (afer 4pm). My plan is to go to Malaysia through HK. Can you tell me the best way to travel to HK in order to catch the 4pm flight from HK to Malaysia? People suggested stay in Yichang for one night because of the flight schedule. Then fly to SZ before taking the shuttle but to HK.

How long will it take if travel from SZ vs. Guangzhou to HK? The airfare is almost half if flying from Yichang to Guangzhou vs. SZ. What is the most efficient and cost effective way to travel for this trip? Pls kindly advise. Thanks.