hello and welcome to GoY.

as long as they are in good light and frost free they should be ok. but as a method I don't use it as it wasn't the way I was taught. You can take the cutting and put into a good compost but dont water until the following day. the stem forms a 'callous' as it dries and then roots grow away. again good light and frost free.
but do which ever method works best for you. You could do some as cuttings and others as whole plants.

You can do it now if you can provide the right conditions. I do question your method. Why would you propagate water roots for a terrestrial plant? If you then try to transfer it to potting soil it will be stressed to develop a whole new root system for that medium. They often don't make it. Better to propagate the cuttingos in the medium it will be living in to start. Consider using a sterile compost keeping it barely moist

As they are semi succulent it is sometimes preferable to use a gritty well drained compost until its rooted. August is usually the recommended time to take the cuttings though. If you use water instead you may well find the stems rot, especially now its winter when the plants slow down a lot.