LCHF impact on fasting BG - How long must I wait?

I was just wondering how long it took (days/weeks/months) before you saw an impact on fasting BG? I've been LCHF for only a week, I've never tested BG while doing keto, and I want to know what my expectations should be realistically. All my levels except fasting BG have flatlined to around 6-7. My fasting is still 8+. I'm not counting my carbs, but I have a bit of a clue of where the carbs are at, and I'm avoiding all of them (meat, eggs, dairy, baby spinach and a bit of tomato for flavour, only water and a coffee in the morning with cream, no sugar). My ketones are in the + so I know I'm in the zone. I've also lost 2kg in 3 days. Any advice? I'm keeping my eating within an 8 hour window (10am - 6pm). This is probably not sustainable in the long term, but I know from past experience that if I get a really good start, it is self perpetuating. My issues will start in a couple of months when it's all too hard! I'm the heaviest I've ever been at 104.5kg initial weight, now 102.3.