There’s no rush, you have to remember that everyone is on their own university journey. Some people know by the beginning of year 12 what they want to study at university, hence booking open days is the next logical step.
Some people apply to Oxbridge, some don’t. Some people visit universities in year 12 and send their application in year 13, others decide a bit later in year 13 and rush slightly, others find the whole university process too stressful and time consuming during sixth form and thus apply during a gap year.
Please don’t compare yourself to others, everyone is on their own university journey. It’s perfectly fine that you don’t know what your next steps are yet, for you have a lot of time to think and discuss. Don’t rush it, open days run all throughout the year so you’re not missing out on anything.