[tag:1ypdvwnu]coljadu[/tag:1ypdvwnu], you aren’t visiting Ladakh, you are merely measuring miles. I’m not sure why are you undertaking this trip. It is neither a vacation, nor an adventure. It’s just transit. I’d strongly suggest you use this time to properly explore some other Himalayan destination.
But if you must insist, here are my comments on your plan –
1. 6.30 PM bus from Delhi to Manali will take 15 hours so I doubt it will reach Manali by 9AM.
2. You don’t need inner line permits anymore.
3. The Leh bus should reach Manali by 8PM and you will get overnight buses from Manali until 9PM.
Please make all bus bookings in advance.