He's allowed to any time after the final decision of Chupp, which was when he filed the 5 page dumpster fire, so long as it's within (I think) 20 or 30 days after the final decision. Thomas has no idea what he's talking about, because he only ever has to deal with cases he's already lost being appealed for his own ineptitude.
It's 20 days because all appeals from the grant or denial of a TCPA are accelerated.
Here's one analysis of it from the appeals court in Houston:
"Because the trial court granted the appellees' section 27.003 motion to dismiss on March 3, 2014 and issued its final judgment on March 25, 2014, Spencer's notice of appeal was due by April 14, 2014. Spencer, proceeding pro se, filed his notice of appeal on May 2, 2014, which was thirty-eight days after the final judgment was rendered. Hence, Spencer's notice of appeal was untimely. See Tex.R.App. P. 26.1(b), 26.3 ; K.A.F.,160 S.W.3d at 927."
Spencer v. Pagliarulo, 448 S.W.3d 605, 606 (Tex. App. 2014).
So if it's right the date would start ticking upon the issuance of a final judgment, not the granting of the motion, which would be interlocutory. If it isn't, the date starts ticking earlier.
I wouldn't even bet on Chupp actually issuing a final judgment in anything like a timely fashion or possibly even knowing he should do it.
You'd have to be a fool to gamble on it since filing too early is completely harmless and filing too late is catastrophic.