So basically our airdrop will finish within 1 month if the circulating supply rising like this, right?
No, this is not correct.
The following will use simple numbers.
Let‘s expect a circulating supply ~11.000.000 BTX. Then there will remain ~ 5.000.000 BTX for the weekly airdrops.
Due to the fact, that only registered wallets are eligable for the airdrops, i think max. 5.000.000 BTX will be part of the airdrops. (There are tons of BTC holders, that will not move any Penny just for this project within the next months. And i don‘t expect Satoshi Nakamoto to do so at least

) For example: there were only ~ 600.000 BTX claimed from the April Snapshot. And even my thought about those 5.000.000 BTX seems like scraping the sky, the more i think about it....
Now the simple math:
Week 1: 3% of 5.000.000 = 150.000 (remaining 4.850.000)
Week 2: 3% of 5.150.000 = 154.500 (remaining 4.695.000)
Week 3: 3% of 5.304.500 = 159.135 (remaining 4.535.865)
Week 4: 3% of 5.463.635 = 163.909 (remaining 4.371.956)
Week 5: 4% of 5.627.544 = 225.101 (remaining 4.146.853)
And so on....