Ok. I did hit and trial. And got weird output. For few tiles, they start spawning little earlier means left side of tile. But after passing few tiles they were spawning in space again.
I set Y to -5000.
Edit: Even if I set it to -10000 then they spawn at complete left side of tile. Means left side of space and as soon my playing start passing tiles, they start spawning little right then right and so on. And finally spawn in RHS of tiles, in space.