This is actually quite normal; many renovations take a little longer than planned. But you're right, the stability of the flooring is the most important thing. A solid foundation will make the rest of the renovation process much smoother for your husband.
I can sense your anticipation for this room. The gradual process of it taking shape is quite rewarding. It will definitely be very meaningful when it's finished at the end of the year.
I'm a little curious, are you planning to use this room as a bedroom or for some other purpose?