Is it ok to visit US on B1/B2 visa while my H1-B is petition is yet to get approved and stamped

I got selected in H1B lot and my petition needs to be approved. My employer wants me to travel on B1 (having valid B1) by next month( September). Will there be any risk for my H1B, if I am entering US with B1 when my H1B is under processing

No its not relevant. Although you might get questioned if its the same employer regarding B1 restrictions. Just prepare for that