Yes, the Sube kit can be used for preschool as the core curriculum and more
importantly, it can grow with them. So for the 2 year olds you will only use
a portion of the activities and then every year you add more advanced
activities so that when they get to age 5 they will have easily mastered the
basic Sube core curriculum. The Sube beginner kit is adaptable for preschool
through 5th grade students so you can imagine, it has a lot of activities,
or versions of activities, that you will  not necessarily use for the 2-5
year olds.

You will also want to supplement with manipulatives as much as possible and
remember that for the little ones, 30 minutes of the structured core
curriculum is usually enough. If you have an hour, free play, more singing,
movement and art projects while being immersed in the language is
recommended.