How soon after Ultherapy and/or injections can I get a Halo treatment? Can they be done on the same day?

This will depend somewhat on the parameters utilized with the devices and the depth of injections, but in general there should be no problem using them on the same day. Most advanced practitioners are very capable of utilizing multiple modalities on the same day.
To ensure you are receiving the highest level of care, seek out a modernly trained, new-school dermatologic surgeon, oculoplastic surgeon, facial plastic surgeon or plastic surgeon who is board certified and fellowship trained in one of these "core four" cosmetic specialties. Membership in organizations like the American Academy of Facial Plastic and Reconstructive Surgery help to identify a highly trained surgeon.
Cameron Chesnut#realself500 Physician

Great question. In most cases, Ultherapy and Halo treatments can be combined into one procedure. However, it is important to discuss this with the dermatologist or plastic surgeon administering the treatments, as it will sometimes depend on the depth of the Ultherapy treatment. Make sure you choose a doctor who is experienced and well-trained in these specific procedures, as you want the safest and best results for your face. Good luck!

It is not recommended to do them in the same day. There is too much inflammation. It is also not recommended to do Ultherapy before Halo. You can do injections, botox, Juvederm, etc. 2 weeks after Halo. It is always best to consult with your physician or Aesthetician before proceeding with any treatment plan.