I would let this grow out as vigorously and strong as possible. You might even consider planting in the ground in the spring. The health of the tree should always come first so let this guy get healthy and strong. Let the candles fully elongate, and let the tree grow as strong as it can. Foliage feeds the root system and pines live and die by their roots. Letting it grow out will speed the development of the trunk as well.
This guys got a long way to go but you gotta start somewhere, right?
Best,
Dan