First and most important, is fermentation finished? What is the SG reading?
If the SG reading is below .996 and does not change for 3 days - fermentation is finished.
Once you are at that point, then yes, addition of k-meta / campden tab(s) is appropriate.
As to when to bottle, that point can be argued until the cows come home. Again most important point - is the wine Crystal clear? Taste is going to change, even in a while wine over time. How much is another point of contention. But bottling a hazy or cloudy white wine.... Why? What's the rush.
Biggest problem for beginning wine makers is to learn patience. Causes more mistakes than anything else. Until you have patience to take time and do things right, you are destined to create wines that could, shoulda been better than they turned out.
I'm almost 3 years into this hobby and I still struggle with letting things work out over time.