Sandy's video link above is an excellent summary.
Adding to it, taking higher levels of vitamin D3 (~10,000 IU's per day) will take weeks to months to raise vitamin D levels substantially from a baseline, typically doubling in ~3 months time. The reverse is true as well. If you are at a high level of vitamin D, say at 100 ng/ml and you stop supplementation and avoid the sun, in six to 12 weeks time, your levels will fall back to about 50 ng/ml (on average).
What is often missing in "news" articles about vitamin D is that it is very hard to raise vitamin D higher and higher to toxicity (>200 ng/ml) when supplementing below 10,000 IU's per day. Vitamin D increase is not linear. Toxicity reports often show the patient took doses over 50,000 IU"s per day for weeks and weeks before toxicity became pronounced. In other words, you would have to be taking 10-20 times the amount of the highest recommended dose of vitamin D3 for weeks and weeks to increase your D levels beyond toxicity.
No one should take more than 10,000 IU's per day of vitamin D3. And by adjusting dose (5,000 to 10,000) during the year you should be able to maintain vitamin D levels in the sweet spot for therapeutic benefit (i.e. 70 - 100 ng/ml). Adding vitamin K2 (menanquinone) to your protocol (200 - 400 mcg per day) will almost certainly minimize any excess vitamin D taken in. vitamin K2 uses D in the carboxylation reactions to keep calcium moving where it needs to go. Vitamin K2 is a sink for vitamin D. They work together. I find I have to take more D3, on average, just to keep my D levels above 60 ng/ml. I have fallen below 50 a few times over the years even when taking 10,000 IU's per day ! (only in winter does this happen). That was a surprise. I test twice a year for vitamin D (March & September).
(*interestingly - when I am out in the Bahamas sun, around noon time with no shirt, my body makes a lot of D naturally (no sunscreen). I do not need to take ANY D3 supplement on these days. This is the only time when my D level has tested around 100 ng/ml.)