Let me explain a little more clearly.

Yes,the will according to Chapman's editon of the letters was proved in 1797(May).

However, the adminsitration of the will , that is the physical distribution of the money and transferring ownership of it, could well take longer, and it seems that,in this case, it very probably did.

Proving a will means that the courts ( Ecclisiastical ones in this instance) accept that is valid( legally OK if you will) and that the distribution of the money/ property bequeathed in the will can take place.

Therefore,distribution takes place after the will is proved to be legally effective and correct.

All stages of probate are completed when the Executors of the will have adminsitered all its provisons and transferreed money and property as directed by the will

I imagine that Tom Fowles money was already inversted in Govermmnet stocks ( to provide him wiht an income)and that the investment had to be legally transferred into Cassandra's name so that Cassandra benefited.

Wheels of adminstration usually,IMH experience ,grind exceeding slow.