Hi,
Five days. Easy.
If you are fit and don't have any unforeseen blisters, foot or leg problems you won't have any problem. I'm a 49 year-old male and I walked it with ease in five days in May 2017. I was not in a hurry. I simply encountered glorious weather and enjoyed being outside walking. I had good feet, good legs and a good head. I loved it. Galicia in sunshine is heaven. This is where I stopped:
Ponferrada to Trabadelo (albergue municipal)
Trabadelo to Triacastela (albergue municipal)
Triacastela to Portomarin (albergue municipal)
Portomarin to Melide (albergue municipal)
Melide to Arca (albergue municipal)
Arca to Santiago (seminario menor)
If the weather had been awful or if my health poor I would have taken 10 days if necessary. But as I said, the weather was glorious and I was having the time of my life. So if you are fit and healthy and have good feet you can easily do this in your time frame. That said, I walked this after having walked for three weeks and I was in prime condition. I was not just beginning my walk as you will be doing so perhaps keep that in mind. My body was used to walking 30 or 40 (or more) kilometers a day and yours will not be.
In any event, just listen to your body and keep and eye on the weather. Enjoy!