Present perfect or present?

how long? present perfect

We use a present perfect to say how long a situation or action has continued up to now. Compare:

• It’s raining again.
  It’s been raining since Christmas. (not It’s raining since Christmas.)
• Are you learning English?
  How long have you been learning? (not How long are you learning?)
• ‘I hear you’re working at Smiths.’ ‘Yes, I’ve been working there for a month.’ (not I’m working there for …)
• I know her well.
  I’ve known her for years. (not I know her for years.)
• My brother’s a doctor.
  How long has he been a doctor? (not How long is he a doctor?)

Compare also:

• How long are you here for? (= until when; when are you leaving?)
• How long have you been here for? (= since when; when did you arrive?)

note

For the difference between simple and progressive forms, (see here).

For the difference between since and for, (see here).

For tenses with since, (see here).

This is the first time, etc

We use a simple present perfect after this is the first time that … , it’s the second … that … , and similar structures (see here).

• This is the first time that I’ve heard her sing. (not This is the first time that I hear her sing.)
• It’s the fifth time you’ve asked me the same question.
• This is only the second opera I’ve ever seen.

note

For present perfect and simple present passives with similar meanings (e.g. The shop has been / is closed), (see here).