Zerohedge has kept track how long it took bitcoin to surpass key milestones in its growth:
$0000 - $1,000: 1789 days
$1,000 - $2,000: 1271 days
$2,000 - $3,000: 23 days
$3,000 - $4,000: 62 days
$4,000 - $5,000: 61 days
$5,000 - $6,000: 8 days
$6,000 - $7,000: 13 days
$7,000 - $8,000: 14 days
$8,000 - $9,000: 9 days
$9,000 - $10,000: 2 days
$10,000 - $11,000: 1 day
$11,000 - $12,000: 6 days
$12,000 - $13,000: 17 hours
$13,000 - $14,000: 4 hours
$14,000 - $15,000: 10 hours
$15,000 - $16,000: 5 hours
$16,000 - $17,000: 2 hours
$17,000 - $18,000: 10 minutes