I flew a lot when both my boys were little. By the time DS1 was 5 weeks on his first flights, 12 weeks the second trip. By the time he was 8 months old he had been to Cairns 3 times, Sydney and Adelaide. DS2 was only 2 weeks when we first flew with him. I have already booked flights up to Cairns for when this next bub will be around 8 weeks old. I have to ring and add her to the itinerary after she is born as I don't have an official name and DOB yet, .
I have found flying with babies very easy. Like the others have said... give them something to suck during take off and landing, take your normal baby outing things on the plane with you and you should be fine. My advice would be to try not to miss out on things that you want to do because you have a baby. If you want to go then go. Babies get used to being out and about if you take them out and about.