Thank you for your question. I forwarded it on to our wild bird merchandiser, and this is the message she sent me to give to you:
Typically, they say that you should be prepared to feed Orioles in early Spring. We are in the northern part of Wisconsin and this year saw Orioles come in as early as mid-late April. It is suggested to line up orange halves along a fence post or along the length of a picnic table to bring them in. If you have Orioles in the area, this should still attract them to your yard, even now. Once you have them coming to the oranges (keep restocking them ), then you should start feeding them jelly (grape is preferred). You can use a jelly feeder for this. Again, keep it filled – one day without jelly, they may take you off of their flight pattern. I hope this helps!