PIP end date soon. NO REVIEW YET

Hello everyone
My PIP end date is creeping up.
They sent me the review form in February and apart from them acknowledging receipt of said form*, I have heard nothing since.
Just wondering how close to benefit end date i shoild get before i rock that boat and call them?
Will they just stop paying me if THEY have not made review appointment.?
They soon penalise us if we fail to attend.
Do they get penalties for not assessing claimants within the time frame?
Thanks in advance to anyone ho knows the answer.
*( filled out in full detail with the help if this wonderful website.
If you are new here, you are definitely in the right place.
Take a deep breath and follow the guides to the letter.
The amazing people and resources totally help relieve mist if the stress caused by DWP and HMRC)