If you aren't ready to go for a formal agreement (I left that far longer than was sensible and suffered financially for a couple of years as a result) at least keep a close eye on financials to make sure spending stays sensible.
I'm re-reading all of these responses as I have been reading some other forums as well so I am trying to align all of the advice.
@Sotto: Can you explain what you mean by "I left that far longer than was sensible and suffered financially for a couple years as a result"?
Why do you feel you left it too long? How would did it impact you financially? What would have been different if you had done it sooner?
