You are not alone
On your first day, one of the main roles of your line manager is to create a welcoming and supportive environment. Therefore, there is much to be gained from acknowledging that he or she is working just as hard to impress as you are.
In your urgency to impress, you could be forgiven for forgetting the role that your manager should be playing.
From your first day onwards, their role should be that of mentor; explaining the firm's expectations and disclosing hidden agendas, while encouraging, supporting or cajoling you.
He or she will also be under pressure to make a good impression on you - remember, the HR department get feedback about staff at all levels.
If the job is not as you expected
Many of us, through no fault of our own, have found ourselves in jobs to which we are patently not suited, or with new colleagues we just don't gel with.
If you have found this to be the case during your first day, don’t panic. Often it takes time to settle into a new organisation and many people have initial reservations, which they quickly overcome.
Before you raise any concerns with your manager, you should complete at least one full week, but preferably two.
It could well be that you have started on a day, or during a period, where everything has gone wrong, and it would be unfair to instantly judge your new company and its employees under these circumstances.
To put it into perspective, you would expect your new employers to give you at least one or two weeks to settle before forming an opinion on you, so it’s only fair that you do the same with them.
If, however, you are still feeling uncomfortable after the first two weeks, you should email or write a letter to your manager (rather than say anything out loud, which could be overheard and misconstrued), spelling out your concerns and asking whether he or she will be able to meet with you to discuss them.
Don’t do anything rash like hand in your notice at this point - any manager worth his or her salt should take time out to make their new employee feel comfortable, and it may be that they didn’t explain certain aspect of the role properly, or that you misinterpreted them.
Once you have voiced your concerns and your manager has responded to them, you will be able to make an informed decision as to whether or not you wish to remain working there.