go ahead

to start to do something:
We've received permission to go ahead with the music festival in spite of opposition from local residents.
I got so fed up with waiting for him to do it that I just went ahead and did it myself.

informal
said to someone in order to give them permission to start to do something:
"Could I ask you a rather personal question?" "Sure, go ahead."

If an event goes ahead, it happens:
The festival is now going ahead as planned.
The launch party will be going ahead as scheduled.
The organizers are going ahead with the scheme despite the objections of local residents.
I'm not sure about the legalities, but I suggest we go ahead with the plan and see what happens.
Until we've got official permission to go ahead with the plans we're in limbo.
Ignoring my protestations, they went ahead and chopped the tree down.

an occasion when permission is given for someone to start doing something or for an event or activity to happen:
The government has given the go-ahead for a multi-billion pound road-building project.
We're ready to start but we're still waiting to get the go-ahead from our head office.

UK
enthusiastic about using new products and modern methods of doing things:
We have a flexitime system and crèche facilities and like to think of ourselves as a go-ahead employer.
(Cambridge Advanced Learner's Dictionary & Thesaurus からの go ahead の定義 © Cambridge University Press)

アメリカ英語辞典
to begin or continue with a plan or activity without waiting, esp. after a delay:
The meeting will go ahead as planned.

permission or notice that an activity may begin:
We’re ready to start the project but we’re still waiting for the go-ahead.
(Cambridge Academic Content Dictionary からの go ahead の定義 © Cambridge University Press)

ビジネス英語
to start to do something:
go ahead with sth The United States can go ahead with the program with or without Canada's participation.

if an event goes ahead, it happens:
The company settled out of court on the day before the trial was due to go ahead.

permission to start doing something or for an event or activity to happen:
the go-ahead to do sth Developers got the go-ahead to turn 42 acres of industrial land into housing development.
the go-ahead for sth Airbus wants half a dozen launch customers signed up before it gives the go-ahead for the new aircraft.
get/give/receive the go-ahead It applied for permission to launch the fund in December and received the go-ahead in May.
(Cambridge ビジネス英語辞典 からの go ahead の定義 © Cambridge University Press)

go aheadの例
go ahead
Initially the party leaders felt that if day-care expansion was to be given its final go-ahead the costs loomed high.
Cambridge English Corpus から
It is likely that that relationship exists in most go-ahead companies that look to the future.
Hansard archive から
例文に含まれる意見はCambridge Dictionary の編集者または Cambridge University Press とその使用許可を得ている会社などの意見を表わすものではありません。

- Cambridge Dictionary