It all depends on what tickets you have and car parking. If general admission, if you want to get a good spot to view from, the earlier you can get there the better. People queue for the gates to open so that they can stake their claim to the best viewing locations for GA. If you have a ticket which is for an allocated seat on a grandstand not so much of an issue, but you do need to queue to get back onto your grandstand about 30 minutes before to ensure you get back to your seat in time as all tickets are checked before you go onto the grandstand which causes the delays. Also bear in mind time to park irrespective of whether you have a car park pass for the circuit or have to get the bus from the other car parks and then into the circuit. On the Friday last year it was a little chaotic with the car parking at the circuit as it was the first day and the car park attendants were not up to speed, and then the queues to get in were horrendus. From where we parked we then had to get round the other side of the circuit which was about a 30 minute walk from where we parked. Qualifying and race day were more organised but were even busier and therefore volume of people moving around/trying to get into the circuit increases. Based on ticket sales this year to date however I am guessing every day is going to be pretty busy, if not already, looks like will be a sell out and at that they have added extra grandstands this year due to demand. Also remember there is not just F1 over the weekend, so if you want to see other track action, which starts usually circa 8.30 am you do need to be there early.