After completion of a project how long do I have to invoice owner? This is in Texas

You really need to retain a construction attorney to review and evaluate your situation. 

The statute of limitations to sue to collect a debt is four years.

You do not indicate whether the project is for the owner's home and perhaps the owner's homestead, or some other residential sort of project. You could have a right to file a mechanic's lien under Chapter 53 of the Texas Property Code, or perhaps the Texas Constitution. But you need to have a construction attorney review your situation to avoid filing a mechanic's lien that could be deemed as fraudulent under the Texas Fraudulent Lien Act (which can impose statutory damages of $10,000, or actual damages, whichever is greater, plus attorney's fees).

You should consider preparing a letter to mail by certified mail to the owner to set out your claim and to attach your invoice(s), and photographs of your unpaid but completed work.

Good luck.

Send notice of non-payment

As an original contractor you have 180 days from the last time you were on the job to file the lien.

File a lien for both statutory and constitutional as an original contractor

If not paid then file suit to foreclose the lien.

Unless your contract says otherwise, when your work is complete send your bill and debtor refuses to pay you in full, let a certified commercial collection agency locensed and bonded in TX use all their resourced to collect the debt. This can successfully be done without you putting up any upfront cost and collected on a contingency bases. If for any reason the agency can't make the debtor pay, you can always file suit as a last resort. Feel free to contact me for specific questions or to let me review your contract. Best regards getting paid, Steve