This article is based on my experiences as a Senior Software Developer starting at a number of different organisations over the years.  I have discovered that you follow a number of stages.

Stage 1: Understanding the Company

During the interview stage you are provided with information about the company but this does not tell you much about working at the company.  You will need to get to know the normal behaviour.  For instance, you will find that there are usually numerous rules in a larger company.  Often these rules are ignore but not always.  Understanding how to comply with company standards is a balancing act.  Eventually you should be able to start making your own rules but to start with you will only be following guidelines set out by more senior staff.

You will also need to understand the products and how they are put together.  For example, each company will have a number of tools and frameworks which should become familiar to you.

Stage 2: Finding Your Place

As a Senior you will be reporting to a line manager and they may be reporting to the head of department or a director.  You need to work out what is expected of you.  Normally your job will be to complete work which makes your line manager look good.  The problem here is that you will not be given credit for your work directly.  You will only receive credit from your line manager, not from anyone else in the company.

After you have gained your managers trust you may be allowed to attend meetings with staff outside of your immediate team.  This means that you can get credit more widely.

Stage 3: Leading Your Own Project

At some stage you should be given the freedom to work on your own.  This may involve selecting the best tools for the project and refinement of system requirements.

If you are lucky you may be allowed to work on your own project on the first day but you may never be allowed to work on your own project.

Stage 4: Passing on Your Knowledge

At some point you may decide that it is a good idea to pass on your knowledge to other team members.  This can be done directly by speaking to them or in less direct way.  For example, you could ask someone to fix a bug in your system or add a small feature.  This will help them to understand your approach.

Reasons to pass on your knowledge

Often developers are reluctant to pass on knowledge because they feel that it will reduce their influence. This is not the case; when someone learns from you they may adopt your techniques which helps you to spread your influence.

There are various ways to pass on your knowledge.  You can do this proactively with pair programming, brown bag talks, etc, however it is often done passively with code reviews, coding standards etc.

Stage 5: Promotion

If you are doing well you may be asked to take on more responsibility.  This will be accompanied by a pay rise.  Often employees do not get promotions and decide to leave the company in search of better prospects.

Conclusion

The time taken to complete each of these stages varies enormously and you may never reach the latter stages.  Just to complete the first two stages usually takes at least 3 months but it could takes years.