Just wondering where can you put aquarium plants for a week or until you need them to plant in your aquarium?
Not only can you put your plants in another container, but you should. It is always a good idea to quarantine plants in a separate container for a few weeks before adding them to your tank, otherwise you can introduce pathogens or snails.
Most plants will do fine (short term) in almost any food safe container of nearly any water (but you'll want to treat your tap water, if you use that, since most has chloramine, which will kill your fish and beneficial bacteria.)
With that said, probably the best water is water from your aquarium. That used tank water is full of nutrients for your plant and will also help it adapt to its new environment. Plus it is already treated to remove any chlorine/chloramine.
For up to 4 or 5 days, you can keep them wrapped in wet paper towels surrounded by wet newspaper. You might have some die off, but this is the way they are commonly shipped. I've had hardier species like anubias survive for weeks this way without any ill effect.
For more sensitive plants, just put them in a container in water at room temperature. They'll last quite a while like this. Again you might have some die off depending on how sensitive of a plant they are and how long they are without sufficient light, but they should recover once they get in an aquarium with the proper conditions.
Definitely do not keep them in the bag, the bag will run out of oxygen, and plants should be kept upright for the most part.
Consider putting them in a fish bowl with a micro bubbler if that's available. If a bowl is unavailable, or bubbler unavailable a vase or extra tall cup will work temporarily. You commonly see betta bowls or vases with plants in them so this will be safe. A cup, bowl, or vase may leave part of plant exposed out of the water, but please ensure roots and bottom portion of plant are in water at a minimum- you'd hate for the roots to dry out. The plants will do better in an aquarium with proper lighting and feed, so the less time they're in temporary housing, the better for the plant. Make sure whatever temporary housing you use, wether bowl, vase or tall cup try not to over crowd (tangled plants and roots are more likely to break when moved) and always use plant safe water, by using plant/fish tap water conditioner or RO water.
If you know the exact type of aquatic plant you have, you can look up what type of light it prefers. If it typically desires moderate to high light, consider placing the bowl, vase or cup in a window sill or part of the house that gets direct sunlight exposure. Check to make sure water is not evaporating too quickly and add conditioned water if this happens.