There's no direct way to transfer files from an iOS device to a Windows system. In general, the iTunes backup will depend on the size of data you want to backup. Since the data will be stored locally, your network speed won't matter whatsoever. You can expect anywhere between 1-2 hours for the backup to complete.
Since all the backed-up data is stored on the cloud, internet speed plays a vital part in the backup time. Your internet speed should be up to the mark without any offline issues. For example, at a speed of 2MBPs, it might take you around one hour to back up about 64 GB.
The initial backup of any new device will take considerably longer than future backups. ITunes must build the database file for the first time, a process which may take several minutes.
Normally, preparing iPhone for restore takes around 15 minutes. However, some users reported that “the software has taken over 15 minutes to download which makes my phone exit recovery mode”.
It takes Apple about 5 minutes.
Expect your first backup to take at least an hour (it's better to allow for several hours), then 1-10 minutes each day. The length of time an iCloud backup takes isn't a huge concern, especially after the first one.
At 5Mbps, for example, 100GB should take about 48 hours to backup. A terabyte backup would take less than three weeks. Double your internet upload speed, and you cut that in half.
A 500 GB backup may take a few hours (maybe up to 10, give or take). If it's a USB connected drive, it may take longer. I would figure the estimate will eventually adjust properly; just let it run.
At a nominal effective speed of about 450 KBytes/s I would estimate about 30 hours, more or less.
Your phone will store up to the last seven days worth of local backup files. Local backups will be automatically created every day at 2:00 AM and saved as a file in your phone. If your data isn't stored in the /sdcard/WhatsApp/ folder, you might see "internal storage" or "main storage" folders.
It depends on your data amount, iPhone condition, and Wi-Fi condition. Overall, it may take 30 mins to 2 hours to backup your iPhone for the first time.
Before getting started, realize that it can take a while to complete a device restore from an iTunes backup. Waiting an hour or two to complete is fairly normal depending on the size of the backup file.
Should take approximately 15-20 mins depending on your wifi or internet connection speed. Depends whether you backup to iCloud or to iTunes. Backing up that amount of data to iTunes usually takes about a couple of minutes or so.. depending on the speed of your computer.