I can vouch wait for a good weather window , I went end of April , brilliant first day got in the mileage I wanted , woke up the 2nd morning tarp covered in snow and it just went downhill for the next couple of days before giving it neck , even the forest roads were 12” deep in water , and the plateau above Llandovery was a knee deep bog in places , great ride but would have been 100% better with firm ground ( some bits may be slightly over grown with nettles etc later in the summer though)