1- How can I start a sentence with : Vainly
2- Is this a proper form : Hardly did I arrive when...
Or : Hardly had I ..........
I've never seen a sentence with Vainly.
Time expressions such as hardly, barely, scarcely, no sooner, refer to an event which quickly follows another. They are usually used with past perfect, although no sooner can be used with past simple.
Hardly had the train left the station, when there was an explosion.
Scarcely had I entered the room when the phone rang.
No sooner had I reached the door than I realized it was locked.
No sooner was the team back on the pitch than it started raining.