Bitcoin's third block reward halving is still 35 days away, but around 11:00 Eastern Time (or 15:00 UTC) on Wednesday (April 8), Bitcoin Cash will have its first block reward halving.
According to data from CryptoCompare, in the past 7-day period, the price of Bitcoin Cash (BCH) has gone from $218.48 to $273.44, i.e. up an impressive 25.15% against USD, as you can see from the BCH-USD price chart shown below:
As for the past 24-hour period, BCH-USD is up almost 6%.
In fact, currently, the top two gainers amongst the 50 most valuable cryptoassets (by market cap) are the two forks of Bitcoin that have their block reward halving this week, i.e. Bitcoin Cash and Bitcoin SV (which is up almost 13% today).
Per data from Bitcoin Cash block explorer Blockchair, at the time of writing (08:18 UTC on April 8), a major milestone for Bitcoin Cash, i.e. its first block reward halving is happening in approximately 6 hours and 28 minutes, which is when block #630,000 will get mined.
So far, 629,960 BCH blocks have been mined, and there have been 287,234,155 transactions.
Bitcoin Cash "block reward halving", or just "halving" for short, is the event that results in the halving of BCH rewards given to BCH miners when they manage to verify a BCH block and add it to the BCH blockchain (a new block is produced roughly every 10 minutes).
When the upcoming BCH halving occurs, the BCH block reward will go from 12.5 BCH to 6.25 BCH.
Approximately, every four years, i.e. after every 210,000 blocks have been mned, the block reward halves, and this process continues, until the block reward reaches zero (which will happen by year 2140).
Currently, the number of BCH coins in circulation is 18,374,490, and of course, as with Bitcoin, the maxium supply is capped at 21 million.
Bitcoin's third block reward halving is occurring in 35 days, i.e. on May 12. The reason that BTC and BCH have different halving dates has to do with the difficulty adjustment algorithm.
Here is some background:
"Both Bitcoin, as well as Bitcoin Cash, use a proof-of-work algorithm to timestamp every new block. The proof of work algorithm used is the same in both cases. It can be described as a partial inversion of a hash function. Additionally, both Bitcoin and Bitcoin Cash target a new block to be generated every ten minutes on average. The time needed to calculate a new block is influenced by a parameter called the mining difficulty. If the total amount of mining power increases, an increase of the mining difficulty can keep the block time roughly constant. Vice versa, if the mining power decreases, a decrease of the mining difficulty can keep the block time roughly constant.
"To keep the block generation time equal to ten minutes on average, both Bitcoin and Bitcoin Cash use an algorithm adjusting the mining difficulty parameter. This algorithm is called the difficulty adjustment algorithm (DAA). Originally, both Bitcoin and Bitcoin Cash used the same difficulty adjustment algorithm, adjusting the mining difficulty parameter every 2016 blocks. Since 1 August 2017, Bitcoin Cash also used an addition to the DAA, called an Emergency Difficulty Adjustment (EDA) algorithm. EDA was used alongside the original DAA and it was designed to decrease the mining difficulty of Bitcoin Cash by 20%, if the time difference between 6 successive blocks was greater than 12 hours.
"EDA adjustments caused instabilities in mining difficulty of the Bitcoin Cash system, resulting in Bitcoin Cash being thousands of blocks ahead of Bitcoin. To address the problem with stability, a change of the Bitcoin Cash DAA was implemented and the EDA canceled. The change took effect on 13 November 2017. After the change, the Bitcoin Cash DAA adjusts the mining difficulty after each block. To calculate the difficulty for a new block, the Bitcoin Cash DAA uses a moving window of last 144 blocks."