It's never too early to start teaching children basic habits of cleanliness and order. I've given a 5-month old a sponge - she watched me wipe the table in front of her high chair, then played with it, practicing basic fine motor skills. Role modeling is a hallmark of the Montessori philosophy. Starting without any preconceived notions or judgments, children genuinely enjoy cleaning. The squeezing of the wet sponge, the soapy bubbles, scrubbing being a gross motor physical motion: think "wax on, wax off". The power of role modeling is also at play here - if you do it joyfully, they want to do it too!
References, philosophy, and pics of the last 10 years documented below: