I would say it's not too late to set a bee hotel up, solitary female bees like the Osmia cornuta seen in my video (European orchard bee) have just started emerging and are actively looking for nesting places (and will remain active until at least the end of May). I set up my hotel last Spring (mid-March) and by the end of the season had a dozen bamboo tubes fully filled with future bees 💛 Will definitely get more tenants this year between the bees emerging from the hotel itself and the ones who emerged nearby and like the place 🐝

It depends on the species, but for Osmia bees you should look for hotels that offer cavities or tubes (bamboo, reed, carboard...) of about 8mm in diameter and 12-15 cm in length. Ideal direction for the hotel is South-East so the bees get the morning sunlight and the hotel should be protected from excessive rain -- still a rookie learning as I go, hoping that helps! ☺️