I've moved this to the Visa Issues Forum.
Note it is in relation to Phuket Immigration Office!
Things which I spotted of particular note were:-
4.1 In case of applicant applying for permit to stay on the basis of receiving income while staying in Thailand (as listed in 3.1), the documents must be issued by the original source less than one month before the application date.
Thus it would not be acceptable to them to produce a previous year's confirmation of income letter, or indeed a copy.
and
4.2 In case of applicant applying for permit to stay on the basis of having 800,000 baht in a Thai bank account, applicants must provide a letter from the Thai bank and a copy of the bankbook showing the three months before the application date, proving that there is 800,000 in the account
4.3 In case of applicant applying for permit to stay on the basis of a combination of income and money deposited in a Thai bank account (see 3.3), applicants must show documents according to requirements listed in 4.2 and 4.3.
So in this latter scenario, (where a mix of money and income is being used), the money must have been in the account at least 3 months previously. Though I suppose that is logical.