I am using "now" to save the block timestamp details. But there is a warning to avoid its usage. If we need to avoid it what is the best alternative to it.
The use of
block.timestamp (which is what
now is an alias of) is often discouraged because it is somewhat manipulable by miners. This is only an issue if you need the time to be precise to within ~90 seconds, if you care about longer time scales where precise timing is unimportant then
now is perfectly fine.
The community likes to use exact things like "block numbers" which cannot be tampered with by the miners.
The now / block.timestamp can be manipulated by the miner to a certain degree as it relies on the machine's time that actually found the block, and that's why the linter is telling you not to use it.
If you're not using that time for really important things like "awarding value to winners" you're fine using it.