Now you switched to timer1
* it is a 16 bit timer, now you could use divider of 8 to get exact 1.000ms --> you are loosing accuracy
* now you have ctc available, but you don't use it --> you are loosing precision
I don't know about CTC. I was writing code for an existing hardware. If Timer1 COMPA is used then PORTB.B1 was not working. So, I switched to OVF. I tried with Timer0 but didn't get exact 1ms and hence tried with Timer1 OVF.