i am gonna post this kind of guessing, because i am curious that what will ever happen when the block is just halved and/or it is just happened. anyone? 
you can't really tell when it is the start of the halving (when the block reward halves) because the real effect of halving which is affecting the supply should take a while to show itself not right after it happens.
so any change will be because of hype and not the real effect so it is not so predictable.
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i got an idea that to trade more with bitcoin to gain more popularity/demand of the bitcoin. 
i don't really understand this, trading bitcoin will not increase popularity of bitcoin!
trading means buying and selling bitcoin and it will also not change demand because you are also selling when you want to trade bitcoin.