From friend's blog

3-6 months

BABY GEAR:
Baby Bjorn, bouncy seats, play mats, swings, gliders, exersaucer, high chair, bumbo seats, johnny jumps & more! You can't have too many toys, since babies get disinterested in the same old thing after awhile. I like to rotate what we do throughout the day, and I have Mason play in his exersaucer for a while, then I will hold him and read a story, then he has floor time, then I carry him around with me while I do a few things through the house. That way he doesn't get bored, and isn't sitting around not being stimulated throughout the day! It's nice to put him in the swing while I get ready, or do the bills, and then I take a break and play with him, etc. By 5 months, though, Mason didn't like his Glider, swing or bouncy seat any longer, and has only enjoyed sitting in his Bumbo, his exersaucer or johnny jump. It's nice to have a highchair when you start them on solids, or a tray that fits on the Bumbo. I think I will just invest in a decent high chair during these months.

CLOTHES: 
3-6 mo. old onesies (15 of them)
I have several cute outfits and shoes (Robeez) for Mason since we are taking him more places now, and people are seeing him. Hello! He has to have a matching little outfit with shoes to be seen in public! : )
BIBS - (lots of them)
Mason isn't a giant, but he fits into 6-9 month old clothes at this age too, so be sure to get all your baby's clothes out because they could have an outfit that fits him/her now, but you may think it doesn't since they aren't between the ages of 6-9 months!
Rice cereal: 4 1/2 mos...ask pediatrician to tell you when they think your baby is ready.
TEETHING:
I've read that babies begin to cut their first tooth around the age of 6 months, but it all depends on each individual child, and they can begin to cut teeth as early as 3 months. Mason has all the symptoms of teething (at 4 mos.) which are:
excessive drooling, fussiness, wanting to chew and bite down on everything, a slight fever, and diarrhea. It's awful to see him so cranky after I feel like I just got his acid reflux under control! The best thing to do is to give him a wash cloth that has been in the fridge or to give him teething toys. I have had to give him Orajel and Tylenol to ease the pain, and his Pediatrician recommended Hyland's teething tablets which are all natural as well. Poor little babe--it's NO fun!
4 month growth spurt: Mason started waking up several times through the night at this age, and STOPPED napping! If he napped, it was only for 30-45 minutes twice a day. I was going nuts and thinking that something was wrong with him! At about 5 months, he was back on schedule, and didn't need to eat every 2-3 hours like I had been doing with him since his stomach was bigger, and since he could go longer in between feedings.

Corneal Abrasion: keep babies nails clipped and filed so they don't scratch their eye like Mason did...pretty painful! 

Peek-a-boo & airplane & looking in the mirror have all been fun for Mason.

I've also introduced a sippy cup to him.

Lots of floor time during this stage so they can practice rolling over. He gets sick of car seat--mirror and musical toys dangling down. Ocean wonders on the side of his crib to help him know it's nap time. I only play it at nap time. I have a little puppy dog snuggly that my sis gave M, so I give that to him and he holds on to it to nap when he wants to hold my hand.

This is a fun age to go for walks...interested in everything.

Epstein pearls....Mason had one on his outer gum and I thought it was a tooth! Ha! They are just little deposits and are not harmful!

Mason banged his toys into his face a lot at this age. He cut his lip, and the Dr. said to use a little Neosporin, and/or Aquaphor on his cut. You can use Aquaphor on any dry skin on their body. I have also used it for diaper rash and it works WAY better than Desitin. It works wonders! I also put it behind his ears when they get really dry there.