I never put anything on mine (my BB's were already MADE of stretchmarks as i was an A-cup aged 10 and a DD-cup age 12, but i got new ones on my tummy during PG) and they'd faded to silver by about 5-6 months PP. You can still see the silvery lines where they were, but only if you're really seeking - i'd wear a bikini, put it that way (though my chunky thighs are more of problem. LOL).

I wonder if skin-tone makes a differenc? I'm blonde with very pale "irish" skin (transparent it's so pale - my chest looks like a road map) and i get stretch marks easily but they fade fast. My GF is very dark with olive skin, it takes a lot for her to stretch (waist went from 23" to 40" during PG and she didn't get the stretchies until the last month) and she only got a few stretchmarks but they took more than a year to fade. But fade they did.....