I think it's way too early but hey ho!
I have one dc who is at O, one who failed to get into O, one may be applying next year for a very obscure subject with very low acceptance rates, but needs to find out a bit more.
I've been on these mumsnet threads before and they always are far more heated than you could ever guess. They tend to go the same way - they start nicely, people claim they aren't that bothered - they know it's a long shot. Some useful advice is offered.
At some point a bitter row erupts usually about state v private, people with children already at Oxbridge or (worse) who went there 25 years ago give (imho) sometimes good but sometimes very dubious advice. Then there's another row when people do and don't get interviews about the unfairness of the process towards state applicants/private applicants/foreign applicants/middle classes/posh/working class.
More upset and rows during/after the interviews and then huge upset/usually reasonably discreet delight when the offers finally come in in January. Always followed by an argument about whether the admissions people are uniquely skilled at pickign the 'right' candidates (usually the line of parents of successful applicants) versus those arguing it's largely luck if you get a place or not. Everyone gets much more invested than they claimed and even truly believed they would. I'm sure I will, even though I should know better by now.
Oxbridge's admissions process is designed to make those two universities seem special and different but there are many other great unis out there. Bear that in mind and make sure your child is very aware of this and keen on their other options. Make sure you are too. It's a trope on here but you will have more fun and free time at another university (at least that's certainly 100% what I've witnessed with dcs' peers) and your life chances will not be damaged in any way, although you and your child may be upset for a week or two if they don't get in. Life will go on.