The challenge of the early morning flight is to stay in the air when the thermal conditions are weak and the thermodynamic wind on the hillside is insufficient to ridge soar.
The official landing fields in the valley are about a 4.5:1 glide from take off because the slope of the hill is so shallow. You cannot, therefore, wait for too long once in the air for thermals to kick off or you may find yourself too low to reach the valley. The situation is anomalous to being on a glide going XC. You have 900m in hand, and must divert your glide path over the spots best suited to trigger thermals or else you will be landing within about 5km and in less than ten minutes.
You should think primarily about the contours of the hill and the unequal heating sun of the various faces of the slope and valley. Early on there will be very little anabatic breeze, as the thermals on the hill will not yet be strong enough to set up the flow. However, almost as soon as it is ®stay-upable®, there will be air drawn onto the hillside to replace the air moving up in the thermals. This of course maybe very light and the flow early on will usually be different to that later in the day as the sun moves higher and westwards and the thermals become stronger.
Take off is at the top of a wide shallow bowl facing northwest. It is not in the centre of that bowl, but off to the east. So after take off you are closer to the spine on the right (to the east) running out, and which has a more west facing orientation (I call this the Bees spine because of the Beehives in the midway landing fields). The spine on your left is further (around 700m) and topped by the Peña Negra boulder (We call this the Chalet spine because of the cluster of chalets half way down it).
This early morning sun will warm the north easterly face of the Chalet spine. On a light wind day this will set up a very gentle flow from the North around it. There will normally be good climbs along that spine, all the way down to the landing field in the valley. There are three spots it along which generally works best. The hairpin bend just beneath the Peña Negra rock, the Chalets and the lower section of the forest. The angle of the sun on the valley is greater than that on much of the shallow slope of the hill early in the morning, so we can often expect to have some of the better climbs when you reach the landing field itself.
Most west to northwest facing mountainsides do not normally work effectively till late afternoon when the sun comes more directly onto them. If the mountain at Piedrahita were steeper, this would also be the case. However, its shallow slope allows the sun to start warming it from early in the day. Thus, although the shallow slope makes us have to glide a long way to reach the valley, this very characteristic allow us an earlier onset of the upslope thermal breeze.
If there is any amount of westerly flow at take off then you should consider flying to the Bees spine. The westerly will indicate two possibilities.