I think your ds is quite young, isn't he? There is no real rush. Why don't you take your time and find the teacher you are really comfortable with for him? You could tell this teacher that you thought the trial lesson went very well but you are undecided atm and can you get back to her in the new year?
Keep asking around for recommendations, if that is what you want to go on. Maybe try and find another teacher for a comparison at least.