I've been doing my PhD for about six weeks now. I still have no idea what I'm really doing, I'm just reading into a very broad topic. Is this normal? My reading can also be a day reading a 4/5 page paper and understanding only 80% of 3 key points. I feel I should at least know what problem I'll be working toward solving by now.
I did a lot of reading at the start too, trying to find a gap in the literature as well as trying to understand the field better. Even when I did have research questions and a proposal, they changed over time. I wouldn't worry too much at the six-week stage - just keep talking to your supervisor about your ideas.
There's no right or wrong point at which things click into place. As chickpea said, your research question changes over time and even after data collection/analysis. My advice is to just keep writing your ideas. Write everything that comes to mind no matter how big or small it might seem.
I started my PhD with a very specific idea about what I wanted to research and how I was going to go about it (for the funding application), and it has changed completely since then. Nature of research! :)
I didn't know properly at least until I scraped through my first upgrade, so probably not til early year 2. In year 1 I read, and wrote, some rubbish. But keep all that rubbish, might come in useful one day.
From the start I knew what I wanted to do. That changed when those experiments went to a bit of a dead end, got parcelled up as a 'negative result' chapter. Took about a year to figure out what I'd do from there. But that year involved a lot of valuable troubleshooting and thinking.
Not at least until the 2nd year (part-time). And even then there were periods when I went off track and lost what I was doing, then had to try and find it again. It's a natural and normal part of the process. My PhD project 6 weeks in was radically different from my submitted thesis.