This festival generally takes place in the month of July
The best time to come to Lampang is from November to April. There is no time of year when it is not advised not to come to Lampang although in August and especially in September it rains more.
We are one week away from Chinese New Year (January 25th, 2020) and despite a lot of mail and detailed information requests from various Tourist Offices in several cities, I unfortunately did not get all the details that I would have liked...