There's a bit more info that would make it easier to answer- what size are the images, how many, what size is the comp? Depending on these you can do one or the other. If you have huge images and lots of layers you go the PSD route, optimize your final output for AE and bring that in. If your images are optimized for video and you do not have a ton of layers, working inside AE in a precomp gives you maximum flexibility without eating up too much RAM.
Also, there's no need for time remapping unless you have movement in your comped image.