Are there any early morning buses from Guangzhou? Where is the bus boarding point in Guangzhou and ticketing offices??

My return flight from HK to India is of 20th April at 14:45. I need to report at HKIA by 12:00 noon. How can I reach there by that time from Guangzhou ( Canton Fair)? Are there any early morning buses from Guangzhou? Where is the bus boarding point in Guangzhou and ticketing offices??

Please advise. Thank you