One of the biggest mistakes my husband & I made was with our son. When he was around 5 months old, he got his first earache. So inevitably we let him sleep in our bed. Then he kept getting earache after earache. So he continued to sleep in our bed. When he was 10 months old, he got tubes put into his ears. But by that time, he had already gotten accustomed to sleeping in our bed. It took EIGHT more years before we were able to get him OUT of our bed!!!
Although my son is almost 10 years old, he still likes to sit in bed with us. BUT, he no longer sleeps with us. Unfortunately, he does NOT like sleeping in his bed. So he usually ends up falling asleep on our couch. It's been a constant struggle. But it is, what it is.
Once our daughter came into the picture, we make sure she sleeps in her bed. Of course every once in awhile she ends up falling asleep or comes into our bed. But it's NOT a constant problem like what we had with our son. In fact, she LOVES her room and her bed.

