Question: I've been working at a newly established firm for over a month and I haven't signed a contract yet.

HR kept telling me that they needed time to prepare contracts for everyone, but I've asked almost everyone else in my department and they've all said that they signed their contracts 2-3 weeks ago.

I asked the HR girl again and she said "Wow, you haven't signed your contract yet? Ok let me check and see what happened".

I agreed to a starting salary until signing the contract, and was told that after signing the contract the salary would be set depending on my position.

The firm has come together in a somewhat experimental way, allowing people to fall into their positions naturally.

Now that I've been with the firm for over a month, is it to my advantage or theirs?

Can I leverage the fact that I'm now established and comfortable in my position (i.e. they would need a few weeks to train a replacement to my level) and can I use this to negotiate a higher salary?

Or is it to their advantage?

Answer: 
That said however if you're going to cut your losses on a recent hire the sooner the better and a month really isn't that long in the grand scheme of things and for a company that hasn't even finalised the exact role the candidate will be performing yet those few weeks of taining will be as nothing. So in short you really don't have much (if any) leverage and I would say that if anything they are in a better than average position to just drop you if they percieve you as looking to hold them to any kind of "ransom".

**PS:** This whole model of making the staffing up as they go along sounds super weird to me. Sounds like they have the organisational/planning skills of a drunken blindfolded donkey!
Not having a written contract is usually bad for both sides, but almost always worse for the employee than for the employer.

The reason is that when there is a disagreement about how much salary they need to pay the employee, then the employer is in a much better position. They can withhold payment, but the employee can not undo their work. Also, the employee is usually more dependent on their monthly salary than the employer is on their work. So the employer can bide time until the employee runs out of money and must agree to a detrimental settlement to pay their rent.

So bottom line, you want a written contract as soon as possible. You usually should not even start working without one.