Unfortunately, there is no such time limitation for charging this as a felony offense. The following language is from section 49.09:
(b) A DWI offense is a felony of the third degree if it is shown on the trial of the offense that the person has previously been convicted:
(2) two times of any other offense relating to a DWI.
As you can see, the statute does not provide any time limitations to charge a felony offense. As such, your prior offenses can be used against you to charge this offense as a felony.
I regret that my answer is unfavorable, but please understand that it would be unfair to you (and unprofessional of me) to provide you with anything less than a truthful response.
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