Is 9 months after lumpectomy too late to start rads?

No: No it's not too late, particularly if you have had chemotherapy between your lumpectomy and planned radiation.

Not Uncommon: Most breast cancers are treated surgically 1st; if chemotherapy(ctx) is needed, that usually goes 2nd, followed by radiation therapy (rtx) 3rd. Depending upon the ctx regimen, it is not uncommon for rtx to begin many months after surgery. Of course, with intra-op rt, that occurs at the time of surgery. In addition, 5-day rtx with brachytherapy can be completed before ctx.