So no need to wait for 3 confirmations? Just one confirmation and I am safe?
it depends on multiple factors:[1]
1. amount you are receiving. if it is small 1 is enough. chances of an orphaned block and a successful double spend at the same time of it happening is low enough. but if it is high (like receiving 10
BTC for instance) you must wait for more.
2. network status.[2] sometimes (although rare) there are some issues. for example during the fork that we had last year there might have been problems such as a long chain of orphaned blocks that could have been discarded for being invalid. during these times you must wait for more confirmation.
3. type of wallet you are using. if you are running a full node you can be more sure about 1 confirmation than when you are using an SPV wallet. with a SPV wallet you have to wait for more confirmation.
[1]
https://bitcoin.org/en/you-need-to-know#instant[2]
https://bitcoin.org/en/alerts