I find much more success with fall rather than spring planting as our air warms up far sooner than the soil, causing slower root growth while there is higher water demand from the warmer top of the plant.

I am still transplanting and planting shrubs, and will be doing so early this coming week. I have put things in the ground as late as Thanksgiving, though that is pushing it in my area. I do mulch the ground near, but not right up to new transplants to keep the ground a bit warmer longer and to prevent frost heaving during periods of freeze/thaw, but in general I find the plants do better with less input from me if I transplant in the fall.

If it were me I would move it now, water it well and mulch. The roots should have ample time to get established. My potentillas are semi-evergreen here in Providence, and I would think they would be the same there on the cape, and so some of the leaves will fall and further lessen demand for water from the roots.