Always wanted to visit Portugal. A bit warmer and wetter than here I would imagine...

There must be a reason you can't plant them in the ground right away, which would be best. I don't know how long you can keep them in the bags, but they will have to be kept moist. If the trees are dormant and deciduous, they should also be kept chilled in a refridgerator. If not dormant, they will need to be provided with light and warmer temperatures, probably 10 C. or warmer, and there will need to be airflow in the bags to prevent mold.

If it were me and I couldn't put them in the ground, I'd pot them up right away, then refridgerate dormant plants or put non-dormants in a warm, high-light location.

I take mine out of the plastic, spread the roots out a bit and cover them with damp potting soil or bark chips.

I don't like the plastic because it doesn't breathe, which increases the chances of some pathogen getting started.

They will stay "heeled in" (which is what I am doing) up until they bud out. Pay attention to the bark and don't let it dry out and don't get it too wet.

Of course, plant as soon as possible. If they aren't going to get into the ground, pot them up.

It has hardly rained this season, compared to this time last year when it didn't stop, that's typical of our surprising planet. So thanks for the insight/suggestions both of you. I thought of potting them up too and it makes sense.

Greeting from Figueira da Foz
Ame seu planeta