Hey @v_MONST3R_v.
The shards are tied to the number of packs you've opened rather than your account level. Any time you open a pack there's a chance you can get the heirloom shards, but it's very rare. If you open up 500 packs without ever getting lucky and pulling the heirloom shards, you'll be guaranteed to get them after you open that 500th pack.
/Kent