Cool, this is a great little kit, you should have fun with it.
I did one years ago and really enjoyed it.
I'm with Ales, I would have attached the mirrors afterwards. Reason being is that they will be very fragile while you are painting the body- so be careful with them! There isn't really a right or wrong answer for when to attach them- just that each offers its own advantage/disadvantage.
How are you planning to paint it? If you have any questions, feel free to ask!