No one right answer and anyone who says otherwise is oversimplifying.
The first thing to do is check where the urge to text them is coming from. Ego urges tend to come with anxiety and desperation, and you’re attached to how they respond. Soul guidance feels lighter and more peaceful, doesn’t demand immediate action. That distinction is hard to make but once you get it, it helps.
If you don’t know what I’m talking about or you’re not ready to accept that we all act with ego more than we’d like to admit - you shouldn’t be texting them. If your TF isn’t spiritually awake to the connection, texting could startle them and cause more soul shock, making the separation harder. Doesn’t mean never text them, but just be aware of their state.
Even if you do text them and get a response, sometimes people get a little too excited (understandable) when their twin responds immediately, but then vanishes again within days.
You can also surrender while still being in contact. Most people who reach union are still in some form of contact with their twin. Find that balance where you’re available in the 3D without devoting yourself to only waiting for them.
I would suggest you write what you want to text in a journal first. Ask yourself what you’re actually seeking from that message. Validation? Want to know if they miss you? Or is there a real message you feel guided to share? No wrong answers, just be honest with yourself about it.