IS THIS TIME OF YEAR OK FOR PLANTING NEW PLANTS?
Yes, it's okay, if you do it soon.
Always plant a moist rootball into moist soil.
To do that, (1) pre-soak the rootball by submerging it in water until bubbles stop rising to the surface. (Simply watering a plant seldom is successful.)
(2) Dig the hole the same depth as the rootball and about twice the width.
And (3) Before setting the plant in place, fill the hole twice with water and allow it to soak in.
Next, set the plant in the hole and use the original soil to refill the gaps. Do not "fix" the hole with compost, planting mix, or anything else as that will inhibit roots from extending into the surrounding soil. Also, do not stomp or pack the soil. Instead, settle the soil by watering as you refill the hole.
Plan to irrigate, as needed, if winter rainfall is scarce.