It is expected that the new TON blocks will be generated in each shardchain (a sub-blockchain) and masterchain (the core blockchain) about every 5 seconds. This will reduce the transaction confirmation time to the minimum period.
This quick transaction confirmation will allow you to use Grams for instant payment (Hello, Visa 😉).
New blocks in each shardchain will be generated almost simultaneously. And in each masterchain, the delay will take a couple of seconds because the main blockchain must contain data about all the recent blocks in the sub-blockchain.
Check out our Telegram channel – there's a lot more info about the TON blockchain!