Syphilis is highly contagious when you have symptoms - the sore or the rash.
You are not contagious during the incubation period. However, is that the only contact you've had with your regular partner? If you've had any sexual contact - oral, vaginal, anal - since then, you should let them know.
"if I have been successfully treated for syphilis previously does this make the bacteria move more quickly in the body?" - no.
If this is the second time you've had syphilis, you might want to really consider your sexual activities. No judgement at all, just concerned for your health, and that of your partners. Make sure you also test for other STDs, like gonorrhea and chlamydia, and if necessary, HIV. Those things are infectious during incubation periods.