earlier the better, before it gets hot; winter should be nice at any time.
3 mile round trip, plan about 2 hours; trail leads out from the parking lot, not much shade along the way, so the earlier you start, the better. And bring sunscreen and a hat and water! great views along the trail as you climb, plenty of cactus. Trail ends near boulders with Native American pictographs, look around, there are several. If it recently rained, you'll see small pools of water among the boulders. Several lizards scurrying about. Some pretty large Saguaros nearby.