Already, still, since, for, yet, and just are adverbs often used with the present perfect tense to indicate the timing or duration of an action in relation to the present. Already emphasizes that something occurred earlier than expected. Still is only used in negative sentences to stress that something expected did not happen. Since indicates that a situation has continued from a specific past time or event until now. For specifies the length of time an action has been ongoing. Yet shows that something has not occurred up to the present. Just signifies that an action took place a very short time ago. The positions of these adverbs in sentences depends on the specific adverb being used.

1. Grammar explanation Already, Still, Since, For, Yet, Just
We often use just, yet, still and already with the present perfect because they are
related to the present moment. This page focuses on the meaning and use of these
words when they are used with the present perfect.
Already
'Already' is an adverb used to show that something has happened early, or earlier han
expected.
Already used with the present perfect means 'before now'. We use it to emphasise
that something happened before something else or earlier than expected.
 She has already sent an email to the manager.
Position
'Already' comes between 'have'/'has' and the past participle (i.e. the mid position).
Note that:
Sometimes 'already' may come at the end of the sentence for greater emphasis or to
show greater surprise. This is especially common in informal speaking:
 They've spent nearly a lot of money on it already.
It may also come in the front position:
 Already, the supporters of the newly elected president have occupied the
streets to celebrate the event.
Still
Still used with the present perfect means that something hasn't happened. We use it
to emphasise that we expected the thing to happen earlier. Still (in this context) is only
used in negative sentences.
I've been waiting for an hour and the bus still hasn't come.
They promised me that report yesterday but they still haven't finished it.
She still hasn't replied to my email. Maybe she's on holiday.
Position
Still comes between the subject (the bus, they, etc.) and auxiliary verb (haven't/hasn't).

2. Since
You can use 'since' when you are mentioning a time or event in the past and indicating
that a situation has continued from then until now.
 I haven't seen Lacy since 2014
Position
'Since' is used before a time when something began.
For
'For' is used to say how long something has lasted.
 I haven't seen him for two years.
Position
'For' is used before a period of time: for two years, for a long time, for a week...
Yet
'Yet' is used in negative sentences to show that something has not happened up to the
present time. It is also used in interrogative forms to ask if something has happened up
to the present time.
 I haven't finished yet.
 Have you finished yet?
Position
‘Yet’ usually comes at the end of the sentence.
Just
'Just' is used to indicate that something happened in the immediate past, that is a very
short time ago.
 He has just called.
'Just' comes between 'have'/ 'has' and the past participle (i.e. the mid position).