Johnny-come-lately noun

1. a person who has only recently arrived in a place or started an activity, especially somebody who is more confident than they should be

[TahlilGaran] English Dictionary ▲

Johnny-come-lately
[old-fashioned]
someone who has only recently started a job or activity and has suddenly become very successful.
She denies suggestions that she's a Johnny-come-lately, saying that she has worked for years to get her own show.

[TahlilGaran] English Idioms Dictionary ▲

Johnny-come-lately
a new-comer
He's a Johnny-come-lately and doesn't really know what he is talking about.

[TahlilGaran] English Idioms Dictionary ▲

johnny come lately
n. Someone new in a place or group; newcomer; also: a new person who takes an active part in group affairs before tlie group has accepted him; upstart.
Everybody was amazed when a Johnny-come-lately beat the old favorite in the race.
When it looked as though Mr. Brown had a good chance of winning, many Johnny-come-latelies began to support him.

[TahlilGaran] English Idioms Dictionary ▲