Modify an existing powershell script

I have a script that asks if i want to reboot a server remotely and if i say yes, it will restart remotely. It already grabs the server names via text file. All I need the script to do is instead of restarting one by one, I need it to restart 4 servers and then ask if another 4 would be okay to restart and so on to the next 4. In addition, I need the script to output a file with the time and date of each server that was restarted in order.