I think you might be jumping the gun a bit. I'd suggest waiting until May 1 to start the slips if your target date for planting is May 24. Additional feedback from folks in your area (Canada) might be a bit more helpful.

Agree it is way too early but you can try rooting some of the slips in some damp potting mix to see if they will take. I plant my sweet pots in potting mix rather than water to begin with and the slip do much better for me that way.

I suppose you could also try adding a bit of fertilizer to the water to see if that helps keep the plant going. They need more than water to survive.

Dave

As Dave said, or you can use sand. I let them grow about 4 to 6 inches long cut them off. No roots then stick them in small pots with potting mix and keep them watered good. After a few weeks they are ready to plant out in my garden.
You only want the slip to have 2 or 3 roots. That all they need to get started in the garden. The reason is most of the new roots will make potatoes. If you don't believe me take one and let get a big root ball on the end and plant it. You want get any potatoes. Now do it my way and you will get 5 to 10 lbs per plant in good loose soil. Also where the vine touches the grown keep it pulled up and don't let it root. That way all the potatoes will grow from only the area you planted them. If you let the vine root on up the vine it will take energy from the end where the potatoes grow and they want get as much or as big. I have planted them 1 ft apart in rows. Some people plant them 18 inches apart. But I like 1 ft. I got about 150 lbs of 20 ft row last year. That about 7.5 lbs per plant.