Hi and thanks for posting your question.
The short answer is: When you feel like it is the right time, in your heart.
This situation is different for all couples and circumstances. Now, both parties involved need to feel comfortable enough with each other. Each reaches this point at a different time so someone is always going to be the first.
Don't expect your significant other to say it just because you said it – they simply might not be ready yet. That's the time to express yourself and shut up. Assume he doesn't just yet, keep enjoying each other, avoid freaking him out by trying to get him to say it and let him do so in his own time.
Forcing anyone to do or say something is being pushy and insensitive to the other person's advancement and growth. When it is said, that will be your ‘release moment' when things really get interesting.
Let me know if any of this requires elaborating on or if you've got more questions. We're here to help you.