My daughter is 4 months old and I exclusively feed breastmilk. I stay at home, so I can nurse all the time. HOWEVER, I really wanted to make sure she was ok with a bottle, so I would give her a bottle somewhat frequently. If your baby is nursing with no problem, I would really say it is ok to give him a bottle when you'd like. My lactation nurse said that if you exclusively nurse for the first 6wks, you pretty much eliminate the risk of "nipple confusion". If you know that there will be times when you will be away, and he will then need to use a bottle, my suggestion would be to make sure you are comfortable that he will 100% take the bottle when it comes time! Trust me, I've seen people with babies who refuse the bottle, so for that reason, I have always made sure my 3 kids would also feed from both myself and others with it! But, like I said, with my 4mo old daughter, I give her a bottle a few times a week and nursing is still going great!!
I hope this helps!
Good luck & congrats on your new baby!!