As it is pot grown, you can easily leave the plant in its pot for a few days/weeks before planting it. Just ensure you keep the plant well-watered, and it gets enough sun. Don't leave it for too long, however, as you don't want the roots becoming root bound.
White Potentilla do not need much care or maintenance, except a trim to maintain your desired shape and height. The plant will grow to 1.5m max. but can also be easily maintained as a low-growing hedge (at 1m). Ensure you prune around Autumntime after the flowering period is over, cutting the old branches down to ground level. You must prune at the right time, so you do not risk removing new shoots trying to grow.
To ensure its flowers will thrive best the following year, we also recommend an annual fertiliser or mulch to be trowelled into the soil.