Offices, care homes, hotels and shops decorate at the start of December, so the date that matters is 1 December, not the 25th. Plan backwards from it: decorations and lights first, then party tableware and crackers, then gifts for staff and clients.
Winter warmth is the line most often forgotten. Hand warmers and heat packs for front-of-house, security and outdoor staff are bought by the case and used from November to February.
Seasonal lines ship in 1 week; order by 24 November to have stock on site by 1 December.