Sure it's okay but if fermentation started there is really no need at this point and 12 hours is not a huge amount of lag time. I would say the yeast replicated quite well during those first few hours as evidenced by the shorter lag time.
I will add though that if you continue to use liquid yeast you should be making starters so as not to be underpitching your beer, which you did this time around.
Go to http://www.yeastcalc.com
and plug in the numbers of your batch and date of the yeast as well as OG and you will see the pitch rate needed.
Had you made a starter you would not have needed to start this thread
IMO, no worries!