Line up with the stain on the ground then I recommends the easier way to line it up is with crouching first and you aim toward the end of the hook on the flowerpot and stand up. After which you move your cursor up until you its slightly above the height of the line at the left end of the towel. Then jumpthrow. It can be a bit tricky to learn.

Nade Time till goes off : 4 seconds ( Uses Skyboxes bug)
Fire fades: 11 seconds after throw

Nade Ranking (stars are rated as 5 is the worst and 0 is the best, so the more stars the more challenge/time/difficulty/risk)

Setup Time: ★★★☆☆ (approx. 8-10 seconds)
Practice till Flawless execute: ★★★★★ (approx. 20-30 attempts till you can hit it regularly)
Cost of Failure: ★★★☆☆ (Explodes in the air, bounces back, explodes on roof)
Throw Difficulty: ★★★★★ (Can be easy with practice)

Nade Overall Rating: ★Expert★
|| Expert- A dedicated nade user in game and practices often ||