How do I come out at work (trans)

27-28yo MtF in MA btw, working a state site contract. I've worked for Allied at a different post before and my supervisors knew at the time, but I was choosing to work under my legal name and identity to avoid awkward situations. I've been on HRT for almost a year now and am more comfortable with being out in public. I've just been rehired after taking some time away, and I begin OJT soon. How would I tell my work about this? Any advice?

TIA