@Ant****
then the soonest you could apply for your new extension would be about the 16th of April. (because Phuket allows you to do it up to 45 days early)
Just so you know you'll be on the new rules then :O
You're going to have to have the 800K baht in the bank at least 2 months BEFORE you apply AND keep it in there for 3 months after you apply, Plus, for the rest of the year you'd need to keep at least 400K baht in the account(s)..
Check with the immigration office soon and then move the money if you have to so that you meet the seasoning requirements.