I am surprised the vet didn't tell them this information. I don't think baby formula is good for them. I would get some KMR asap. It comes as powder or already mixed, but costs a lot more already mixed. If you mix it yourself, its easier to make it in a big jar then funnel it into the bottles. But it is only good for 24 hours once mixed and must be kept in the fridge. Keep the can of powder in the fridge too.
After you funnel it into the bottles, warm it in the microwave for a few seconds and check the warmth on your skin (like you do with human baby bottles). You may need to gently squeeze the bottle and keep encouraging them and letting them know what is in the bottle. Some babies are harder to get going than others.
After feeding, get a damp warm cloth to stimulate them to go potty. I usually do it over the trash can, less clean up Don't be surprised if they don't poop for awhile.. it took some of mine almost a week!!! That KMR can get them a little constipated. Don't be worried if you see diarrhea either. They may do that on their own.
I like to have soft classical music or radio talk shows playing for them too.
Its really important to have a stuffed animal in there, especially if its a single kitten. They cuddle up to it like its their mama.
At around 3-4 weeks, I usually start mixing the KMR with canned kitten food into a mushy substance to teach them to start eating on their own (I still give them bottles until they're 8 weeks, but also have them eat on their own sometimes). Around 6-8 weeks, I introduce solid kitten food but I wet it down with either formula or water. Usually a little after 8 weeks, they can eat just the solid food themselves with no more formula.
While the kitten is this young, I would feed every 2-3 hours.
If you have any questions, don't hesitate to email me or post here. I have had around 20 bottle baby kitten fosters this year and only lost one due to a birth defect
Shiloh, Reece, Lolly, Skylar
and fosters Snickers, Missy, Magic, Merlin, Maya