The references are about the first year after planting not the age of the plant. During that first year the plant needs most of it's energy to build new roots. So it's best to remove most if not all the fruit. You can leave a few to taste but very few. Even a foot tall is very small to be fruiting.

I would take all the flowers off the first year, irregardless of how old the plant is. It takes time to become established and get a good root system going. If you leave them, they may grow, or may end up aborting, but will slow down the vegetative growth of the plant. You will be ahead in the long run if you just buy berries in the store this year...