You or your representative must sign the IPP so it can go into effect. Section 4646(i). If you agree on some things but not others, write down which things you agree on and which you don’t. Then sign the IPP so the agreed-upon services can begin, but write near your signature that you are signing only as to the things you and the regional center have agreed on. You can appeal disagreements through the fair hearing procedure.
The things you do agree on should go into effect by the date you decided at the meeting.