Mother is actively dying, and I advised her to set up a trust. she has agreed however I have heard third hand a trust has to be set up 5 yrs before

I have an appointment with an attorney to set up a will, living trust and living will, and am trying to determine if a living trust has a time line to set up. My Mother is of her right mind and has made her decisions to distribute her assets equally among her 5 sons. is it too late to set up a trust to avoid probate?