When do I decrease my deficit?

My current TDEE is 2300 and I've been eating at a 1000 cal deficit (so 1300). But as I lose weight, my TDEE decreases and therefore, so does my calorie intake at a 1000 deficit.

My ideal weight gives me a TDEE of 1600 (so my TDEE would gradually decrease from 2300 to 1600). However along with this, my deficit will drop to 600 (which doesn't seem healthy to me).

So my question is... when do I start decreasing my deficit? Do I just continue eating at 1300 even though it will no longer be a 1000 cal deficit? I hope this question makes sense, I know it's a bit wordy.