Parque Nacional Natural El Cocuy
All The Info / When & Weather
The answer to "When should I go?" is, well, when you're in Colombia! The high season is mid-December to early January; you shouldn't have a problem finding hiking buddies during this time. In fact, the park is so popular in December and January that you should seriously consider calling and reserving ahead if you're going to be staying in any of the cabanas or haciendas near the park. The hotels and hostels in El Cocuy and Guican generally do not fill completely up, but if there is a place you're set on staying while in town, call ahead. If you're planning on doing the 6 day trek during the high season, you shouldn't have a problem hooking up with a larger group (to cut down costs) in either El Cocuy or Guican. The guides in town will gather groups together, all you need to do is to let them know once you get to town you're interested in doing the big hike.
December to March is also coincidentally the best time to visit the park in terms of weather. Because PNN El Cocuy is mountainous terrain, snow/rain/fog can happen at any time, but the December-March time frame is definitely your best bet for good, clear weather. Regardless of when you go, it will be cold. Check out the What To Bring section for more info on packing. Even in the cabanas and haciendas it's chilly; make sure to buy a hat and gloves (very cheap in El Cocuy or Guican) before you head up.
If you're planning on visiting the park outside of the high season, all the better! Fewer people means more park to yourself. But if you want to do the 6 day trek, you may have a hard time hooking up with other people to split costs with. I'd suggest posting on the Lonely Planet forum, letting people know you're looking for people to do the hike with and when approximately you want to go. Of course the guides will not have a problem taking you alone on the 6 day trek, but it will be relatively expensive.