yes,thats true!we need to stick with the sponsoring employer after I-485 approval for atleast 6 months,or else it may construted by USCIS at the time of citizenship adjuducation " as malafide intent by the employee or employer to obtain permanent residency".So the best bet is to work for atleast 6 months or even more if you have the intent of applying for citizenship,to avoid problems later.
to avoid this situation,many are now-a-days using AC-21,to move to a "same or similar" before i-485 approval,thereby circumventing the uscis stand on this.
hope this helps,and congratulations!
thanks,