How old was your baby when you switched to a convertible car seat?
Also how long was your baby, And how much did your baby weigh? My 3 month old looks like he will be outgrowing his car seat sooner than later...he's about 16.5 pounds and 24' long as of now....and which brand did you get?
thanks : )

I just moved my daughter to her convertible seat last week. She is 3.5 months old and big for her age (17 pounds and 27 inches). She still fit in the height/weight for her carrier, but it was so tedious to carry and it was getting tricky to buckle it around her if she was wearing thicker clothes (I live in Ohio and it getting cooler outside). I have an Evenflo Triumph Advance carseat. It goes rear-facing up to 35 pounds and forward-facing up to 50 pounds. I like it a lot. It gets as high of safety ratings as the Britax but is much cheaper. I also like the fact that she can be rear-facing for such a long time. She seems comfortable in it. A few words of advice: I had the Graco Snugride infant carrier and it reclines much more than the convertible car seats do when rear-facing, so when I switched her, it seemed like my daughter was always slumping forward when she fell asleep. That made me nervous, so I bought a thing called the "Cradler" from Kiddapotamus (at Babies R Us) and that has really helped her keep her head up when asleep. Also, now that she isn’t in her carrier, she doesn’t have a canopy to shade her from the sun. We had some very tough drives as the sun was shining right in on her eyes and she was very upset. If you have tinted windows, that should be fine, but I drive a Civic and I tried several rear window sunshades, but I couldn’t see well enough through them to drive safely. I ended up putting sunglasses on the baby, which seems to be working. She is still too young to pull them off. Sorry for the long post, but I wanted to give you all the help I could since I just went through this myself! Good luck!
1 year
Most Convertible car seats are good 5-100 pounds you just have to keep them facing backwards till they baby is 1y/o
http://www.walmart.com/catalog/product.do?product_id=8207450
My daughter was 3 months old. She was around 23 inches long and 15lbs. I just couldnt lug that damn infant seat around anymore, so we switched to an Eddie Bauer convertible (holds from 5lbs-110lbs). For outings I put her in a carrier and wore her until she could sit up well on her own.
I switched over at 8 months or so. But we still have it rear-facing. He didnt out grow it, we just thought the convertable one was more comfy for him. We plan to stay rear facing for as long as possible.
I switched my son to a convertible seat at 6 months, he is a big boy and had out grown his carrier seat. I bought an Evenflo seat, I really like it. I think his seat goes from 5-100 lbs.
My little guy is 4 months old and we plan on switching to a convertible one very soon. One, it is too heavy to carry around everywhere! I give some serious credit to moms who have to carry around twins! And, I just looked at the height and weight on our carrier – he is 14 lbs but is 27 inches! So he only has 2 inches left before he is too big for it! (o: We have an evenflo one that we are going to put in any day now. It is very comfy looking too, so I think he will enjoy it.
I got a convertible when my baby got to 20 lbs (the max on the infant seat). But you must keep them rear-facing until they are 20 lbs AND at least a year old.
You can keep them rear-facing until they reach the max for rear-facing (usually somewhere between 30 – 40 lbs). I kept my daughter rear-facing until she reached the maximum for rear-facing. They are safer rear-facing, so there’s no need to turn them around until they reach the stated maximum for rear-facing.
I had a Baby Trend Flex Loc infant bucket and I think my son was around 8 or 9 months old before I moved him to a convertible car seat. I would recommend the First Years TrueFit car seat(Target has them online). Britax is also a great brand of car seat. I own 2 Britax car seats and think that they are nice. Try to stay away from the 3 and 1 car seats because they are usually outgrown before they can be used as a booster(and the booster suck anyway). http://www.carseat.org can help you also in making your decision. They have car seat experts on their who can help you.
1 or 2 years it depends on there size some are small in body and some are big