Is there a statement that could included in a Trust restricting when the person to be my agent from being involved in my affairs too soon?

I am studying an updated draft of my Trust. My wife passed away in May, now my 2-sons are to be my agents...one with power of attorney, the other acting jointly. From all the 14 pages of duties, etc that would begin immediately. I wonder if I could suggest to my Lawyer some clause that would define "when' such power over my affairs would begin. I really don't want to have either of my boys telling me whether or not I can spend my money on this soon. Why not wait until I become truly not able to handle my affairs...at which point they then could have full power of attorney. I am 81 years old, healthy, have earned enough money to live comfortably for years and years and have enough common sense to buy and sell without going thru (getting their advice, etc.) my sons first. Please suggest the wording required to include in the Trust...Thank you.