what happens if i take my kids back home with me if their dad , the legal custodian, doesnt pick them up by the appointed time?

That all depends on exactly what the divorce decree orders. You would need to have that reviewed by an experienced family law attorney to ensure the correct advice. If you are talking about the occassional few minutes late, it is not worth the hassle. If it is a one time occurence and he has a good excuse, again it is probably not worth the hassle and costs involved. However, if this is a constant problem then it may be worth it to you to review the facts and the decree with either me, or some other attorney of your choice.