If im making a.roast in the oven what time.should i put it in so it can be done by 5pm?

Ask the butcher, often have could advice, depends on the size of the roast. 350 for 3 hours. I usually have a nice size roast, in large pan, with potatoes, carrots, onion, mushrooms, spices, dab of butter, along with a cup or so of water, put in oven at 350 for 3 hours, take out, drain the juices into another pan, put pan back in oven uncovered, let brown while I make gravy with juices, using corn starch is easier that a flour and butter rue, when gravy is done, take out browned roast (oven is usually off during browning) serve with gravy.