I would start reading for whatever your first rotation is. You can't go too wrong reading Brandt helms so starting with the intro and then going to whatever chapter goes along with that rotation. Set goals for what to read on each rotation that are reasonable and actually accomplish them. Like I would say the Brandt helms chapter plus the accompanying section on radiology assistant (great website) and throw in some case in point quizzes on the acr website to keep things interesting. Radiographics articles are great and the people you work with will usually tell you important ones to read for each rotation.
*disclaimer - I have no idea if I'd have time now to read Brandt helms for each rotation because I did it during my prelim year. I've been reading the book core radiology during my R1 year primarily and it's been great. On the other hand I don't think I would have gotten as much out of it if I hadn't already been through Brandt helms. But I would pick something you can reasonably stick to and not try to do too much and get too behind.
95% of the stuff you do day to day is just learning what's normal, how to dictate etc and takes practice and reading books won't help (which can be super discouraging but it's just the learning curve). But having a good foundation will keep things interesting and you'll end up liking what you do more when you do figure out those tough cases.
You'll find out also that reading CTs can be easier than X-rays because you can see more. Same goes for MRI if you just go for it. So make sure to try and make sense of the MRI fundamentals early. Ultrasound seems harder than it is until you actually get to reading it.
There are people that don't read at all until they study for boards and can seem perfectly fine when you read their reports etc, but if you don't have the fundamental knowledge base you just can't take things to the next step. You're gonna want to be someone who can find specific findings and make calls when they are there to make, which you'll see many attendings can't do outside their specialty.
Also there is a podcast for the journal radiology. I just started listening to that because I find I never actually read the articles as they come out.
Sorry for the long ramble but I had been looking for this answer last year and couldn't find a great answer.