Delay joining the employer in h1b

Hi,I worked for the consultant employer as F-1 OPT, and they filed for my h1b this year, my opt was expired on Dec 6 2016 and I quit the current employer. After the long wait, my h1b was approved with COS on Dec 9 2016. However, for some reason I couldn’t join the employer immediately, I want to wait till January to join them, and I didn’t get pay for that time. I want to ask am I out of status now, and does it affect my future h1b extension/gc filling, also Can I tranfer to the different employer now without any pay stub? Thank you