Central Districts of Bhutan covers Bumthang and Trongsa. Travel to Bhutan has to be for at least over 7 nights in order to witness these festivals as they are at least 2 days drive from the Paro International Airport, unless if the Bhutan Domestic Airline is in operation and so you could travel directly from Paro to Bumthang.
Bumthang is the hub of Buddhism in Bhutan and a very beautiful place with many temples,monasteries and sacred places of visit. Thus Bumthang District has the largest religious local festivals in Bhutan.
The Various Festivals that take place in Central Bhutan are:
Link to WHOLE BHUTAN FESTIVAL DATES YEAR 2023 and FESTIVAL DATES YEAR 2024