Icandy seat... Too soon to use?

I have the peach jogger (glacier) and love it to bits! I purchased it along with adapters for my car seat, and then purchased a (nearly new) carrycot online. The carrycot is actually from a blossom/twin peach... So is slightly smaller than that of the one that should belong to the jogger. Any how, my baby is growing fast and at 3 months is getting too big for the carrycot. We like to go on long walks and I don't want her in the carseat for long periods. She loves to look around and be nosey too! Is it too soon to put her in the seat? I have bought a liner for the seat and sleeping bag to pad it out. Has anyone else used the seat before it's recommended age level?