No. It's in September so it's before the October deadline of this year: "The Information Day is particularly intended to provide a further opportunity for students and parents/teachers who may be preparing an application for entry to Oxford the following year..."
The ideal if you knew more in advance that you were considering it would be the 'proper' Open Day held in the summer (usually late June) = bigger scale (over 2 days) & all the colleges hold their Open Days on the same days, so easier to look around & pick a college...
The Information Day is a relatively recent addition to the general open day programme - in my experience attended by people who did surprisingly well at AS & started considering Oxford, were disorganized/hadn't thought too much about applications yet in June, couldn't make it in the summer, or were super keen!