Depends how fast you want your babies.

In my experience the perfect conditions for rootiong your leaf would be humid, but not soggy soil, close to 100% humidity and let's say 75F. You can achieve it if you put your potted leaves under the dome and throw wet mat on the bottom of the tray. Fluorescent Lights help too. After the leaf is rooted and probably the babies are showing - I would put it in the open on the mat with wick.

In your setup you will get your babies as well- but it will take longer if your ambient humidity is low. Gravel or no gravel - if your house have 10% humidity - you will not get 100% around your plants.

I think 2 weeks under the dome or baggie - will put you ahead probably for a month - because a rootless leaf is not spending any energy to someway absorb water it is losing from its surface - but can use it for rooting. After it developed roots - it will be OK.

Good Luck

Irina

It DOES help to create a mini greenhouse environment. 2 weeks like Irina says is good.