We're all different. For me, nothing changed for several weeks after starting abx. But I don't seem to be a person who has a herx very easily. By week 3 on doxy, my fibro pain was g o n e!!! When two weeks later I was switched to azithromycin, mepron, and artimisia for babesia I was afraid the fibro pain would return, but it has not. I've had twinges here and there, but the crashingly agonizing all-over pain is still gone. So I would say so far your experience sounds normal.
I am not sure a person has to herx to be receiving benefits from their meds. Throughout this thing I have taken holistic cleansing tinctures, drunk detox teas, and somewhat sporadically taken the detox baths. I also drink lots of lemon water daily to keep things flushed out. I don't know if that is why I haven't had a bad herx or not, but figure it can't hurt.
I have Lyme; it doesn't have me.