What is the best time to buy bitcoin?
Bitcoin has significantly decreased in price already, buying now is not a bad idea. Do not panic and just hold, holders never lose but profit if patient enough.
bitcoin deposit recommend wallet?
Bitcoin Core (but need large amount of data to download the full blockchain)
Electrum is highly recommended, you can even use it as a cold wallet
Hardware wallet like Trezor and Ledger Nano are highly recommended for high amount of bitcoin, private key is completely offline
What are your thoughts on Bitcoin minig?
Bitcoin mining is profitable, provided you use the right miner (like bitmain Antminer S19, T17, S19 pro), calculating if the electricity cost in your areas can make it profitable, and joining a good mining pool. To know more about Bitcoin mining, you can open a thread about it on mining board.