If you want the information from your DLA claim then yes use the date of claim, but be aware, your argument that you were awarded DLA and that your condition has worsened since then will not aid a PIP appeal, the criteria for DLA is significantly different from PIP and it is perfectly possible for someone to have a DLA award and not receive a PIP award on transfer.
You will only receive a PIP award by showing that you meet the criteria for one.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems
