The likelihood is you will not meet the financial requirements for the subsequent extension because the 800k was only in your account for long enough to get a statement printed not 3 months post-approval then 400k for the rest of the year
So you will need two bank accounts with 800k at least for your first year extensions then possibly switch to the 65k monthly transfer method (one or both) for subsequent years
A worthwhile alternative is to do it yourself before you travel because doing that means your wife may be able to get a trailing spouse Visa so only one financial requirement for the main Visa holder. Check your Royal Thai Embassy website to see if this is possible.