…and just put the little one in the stroller. Can you do this sooner if you have a head support you can use in the stroller?

This may be a silly question, but this is my first, so I’m just wondering what is the earliest we can do this?
Not this exact stroller, but very similiar:

http://s7d2.scene7.com/s7ondemand/zoom/flasht_zoom.jsp?company=GracoBaby&sku=7F07EMA3&vc=viewSize%3d400,400&zoomwidth=500&zoomheight=550







is the baby trend snap and go compatible with the britax convertable car seat ?

i dont want to buy an infant carrier, they seem like a waste of money so i decided to buy a convertable from birth to 6 years old. i wanted to use the baby trend snap and go but i am not sure if that car seat would fit…

https://www.toysrus.com/product/index.jsp?productId=2934996&fromRegistryNumber=76730350&product_skn=911227

or

http://www.buybuybaby.com/product.asp?order_num=-1&SKU=15144734&RN=7022&