I clicked to respond but see you already have been given the best advice... Hyland's Teething Tablets! All natural and they work immediately. I bought mine at Target and found them to be the cheapest around. But now they have them inside the pharmacy so you have to ask for them and be there when it's open.
My son learned to ask for them when he was teething. That's how I really know they worked! We used sign language and taught him the sign for medicine, which he would do and then point to his teeth and he'd get excited when I got out the Hyland's bottle. He knew he was communicating with me! He got his first teeth around 9 mos, so I'm talking about signing like this closer to a year old. He started signing at 6 mos.
I would only give Tylenol if he had a fever, to bring it down. Otherwise you don't know if you are doping them up. Please try the teething tablets! They are cheap, $3.39 at Target for a whole bottle of 125 tablets. (They are small.) And you only need 2-3 each time so it lasts a while. I'd give 4 or maybe 5 when the molars come in. A friend used 6 when the 2yr molars were coming in. But it doesn't hurt them to have a little more, it's not a drug. Mostly chamomile and other natural ingredients that soothe and numb the gums. I buy them for friends who are having first babies, I put a bottle in with their shower gifts! This is one of those secrets of motherhood you just want to share with everyone!