Oh - we never did anything really academic during the preschool years. We just had a lot of open ended toys around - blocks, legos, dress up stuff, dolls, kitchen toys, etc. And we're always ready to answer questions. We did a lot of active play and cooking in the kitchen. I have 2 kids that showed no interest in reading, but we never introduced them to easy readers until they were 5. My daughter briefly leaped slightly in reading interest at 4 and dropped it again. Both jumped in reading in kindergarten. My son was tested achievement wise yesterday and is at that 99th percentile achievement wise as a 3rd grader, even though he wasn't there at K. He is still the same kid. And he had a lot of knowledge as a preschooler. Just not the kind of knowledge that would be on a standardized achievement test. :-) And I was completely in the dark my DS was even GT until mid-kindergarten (neither DH or I were IDed). It was quite blissful not knowing actually.
I personally think my kids lost nothing by never seeing a workbook that young. They both are very active and have great social skills too. The problem with many standard workbooks for gifties is they are incredibly slow paced and repetitive IMHO. I've picked up a few as filler homeschooling, but have rarely had luck unless they're way, way above level (which sometimes makes the content "boring"). Or they're designed for gifted kids.
