My understanding from a brief exploration of the question on the web is that the named executor of a will can't start processing the property until the will is in probate.
To fill out the petition for probate, you may have to do some basic analysis to determine what’s in the estate. But taking action beyond that — selling assets or making payments — is not allowed until the court has approved your petition and appointed you as the executor.
In the case I'm tangentially involved in (being friends with the people involved), the deceased has two children, the elder female and the younger male. The younger male is stated as the executor in the will, but the will is not yet in probate due to a lost document involved in the witnessing of the will. The older female has been living in the house, and was tending to her mother at the time of her death. The younger male and his wife have started coming in to throw out what they consider to be of little worth to the protestation of his sister still living there, with him claiming that this is his job as the executor (despite the will not being in probate).
I've advised her to consult with a lawyer, because this seems very shady, but I'm hoping to find a bit more evidence to get her to move forward on it because she's reluctant to "start a fight" with her brother (despite he and his wife having already hired their own lawyer).