Starting is one thing. I dont think people understand how long it takes for poor factory workers to get around in huge china and then back to their job. They might very well leave a week or two early early in some cases. It is a huge mess. 130 million people trying to get home and not using jets. Weeks before the holiday things gring to a halt and cause major problems for the largest customers let alone tiny ones.
We always used to count on a two month delay around Chinese New Year. As you said, many places close early because it takes so long for people to travel home. They often re-open late for the same reason. Another issue is that many workers don't return at all so when businesses in the manufacturing sector do re-open they not only have orders backed up but they often have to find new employees as well. Even a business which is not directly affected itself will often have issues because its suppliers are affected.
Of course the fab might not be in China. If it is, though, BLF urgently needs to find out whether it will be closing around the Chinese New Year period or working at reduced capacity.