Would it be a bad idea to try it for the first time alone?
If you do edibles and you're going to a dispensary, you must absolutely listen to the packaging or "bud tender". If he tells you or the package tells you to only take 10 MG, listen to them even if you don't think its working after an hour. Hell, to be safe, take 5 mg and then wait about an hour or hour and half and then take the other five.
Trust me on this. Everyone makes this mistake with them the first time where they wait like an hour and say "this shyt isn't doing anything" and do more and then they are fukked.
Don't try to be brave when you have absolutely zero tolerance.