Hey hey. Welcome to the Nexus!
For PV, you want a 1:1:1 potting soil: perlite:vermiculite soil mix. Lovingly referred to as the "Bach mix." You don't need good drainage as much as you need lots of moisture.
The ziplock bag is good.
The light is probably too much. PV are understory plants and do best in shade to a few hours of indirect sun a day. Indoors they do the best in a windowsill without any or with minimal artificial light.
There's a ton of information on Share the Seeds about PV propagation, but STS is down right now so I can't link the PV thread. I do have some instructions written up that that I'll just post here. It was written for unrooted leaves, but the same holds true for a rooted leaf too:
Soil: 1:1:1 potting soil: perlite:vermiculite. They can go a little heavier on soil as they mature, but the lighter mix is good for rooting. They run the risk of transplant shock, so any changes in soil should be done gradually.
Humidity: Humidity is key. You want near 100% humidity because rooting will take a while and the leaf needs to stay moist to stay alive. Anything from putting the pots into large ziplocks, covering with glass jars, plastic 2-liters, up to more complicated humidity chambers should suffice.
Air Flow: Supply fresh air daily or so (though they've been left to go longer without issue) by opening up your chamber for a few minutes.
Water: Water thoroughly, and keep them moist throughout rooting. Don't let them dry out between waterings, though with the high humidity you may not need to water very often at all.
Light: PV are understory plants. They are highly susceptible to burn with too intense of lights. They do fine near a window, in a shady outdoor spot, or on the outskirts of an indoor light setup. As they get older, they'll do best under a tree so they get a couple hours of indirect light early or late and are shaded during the high-light hours of the day or under a partial shade cloth.
Temperature: Temps in the high 70's to 80's are preferable, but attaching a heat mat will likely dry them too much. They do fine with normal indoors temps. Prior to maturity, temps below 50 F can be damaging.
Forge a Path with Heart <3