9-10 days, that's better than hers - maybe she got a dodgy cheapie one somewhere then! I'm like you as well - I never *ever* tan in the sun - just burn, or get freckles. I'd love to be able to go golden but it just doesn't happen for me. I've found the Ambre Solaire spray on self-tan to be really good as they do it in a light shade, but more pricey than others at £9ish a bottle.
I also have tried that Johnsons Holiday Sun stuff which everyone loves, but it had a weird effect on me and doesn't really sink in properly, then just rubs off! Leaves me skin feeling almost dirty, so I've stopped using it!