growing cuttings

I generally wait until there is some root growth. I gently tap a cutting out of its container without breaking apart the soil. If I see roots at the edges, I remove the plastic.

For a "tent", I take a liter soda bottle, cut the top off, and pry any solid plastic bottom off. (Some bottles don't have a separate solid bottom.) Turning the bottle over, I have a miniature greenhouse.

Some cuttings root so easily and quickly, that I don't protect them at all. These include philodendron and its relatives, chrysanthemum, and ivy.

Supermarkets sell foil casserole trays with plastic covers. I don't see any difference between those and the plastic "greenhouses" sold at garden shops, save for the much cheaper price.

Varies depending on the plant. Usually 3-6 weeks the plant is well rooted. Hardwood cuttings can take 8-12 weeks.

What you are doing is rooting cuttings, so you wait until the cuttings have roots. It can take a couple weeks for some things and forever for others. The standard test is to tug on a cutting and see if there are roots. If there are no roots, then wait another month or two. If there are roots, then if they are well developed, you are done. If they are not well developed, then wait another couple weeks.

When the roots are well developed, then as you mention, start venting the plants to air a couple more hours each day. Never let the media dry out, but don't keep it too wet. It needs to be well drained for most plants.

There are basically 3 general types of cuttings: herbaceous, evergreen, and deciduous. Herbaceous means the branches of annuals or perennials. Evergreen means the woody stems of flowering evergreens or conifers. Deciduous means the woody stems of fruit trees and shade trees.

There is a man in South Carolina named Mike Creel that can root just about anything in 'dome pots". He uses most any clear container for a rooting apparatus. Here are links describing his techniques: