Sometimes newly acquired monitors wont eat for a week or so until they feel comfortable in their new home which is why alot of open space is not a good idea, it makes them feel vulnerable so i tend to crowd the floor of my enclosures with branches, leaves and plants. They can go several months without food as long as they have water and never lose an ounce.
As far worms, my water never took to them but if it eats em just offer as many as it'll take in one feeding. But if you cant get it to take them offer live mice pinkies ive never known a hungry water to turn them down.
A good idea to keep track of what and how much they are eating is place the food in a small dish that you can slide right in front of its hide and leave the room or dont allow it to see you for a few hours then come back and check the dish. If its eaten the contents then add more(small portions of food and refill as needed)and if the foods still there when you return then just take the dish out, it may still be to stressed to eat.
I usually cover the front of the tank for a week with a dark cloth to allow them time to acclimate and never pick them up for atleast 30 days.

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James Grigsby - " When you try of all your forces to make your own way, you will help some of others and will be helped by others. As long as you do not make your own way, you cannot help anybody, and nobody can help you. " (Shunryu Suzuki)