What advice do you have for beginners trying to withdraw their crypto from exchanges?

I’m wondering about the basics.

Is it more expensive to make these withdrawals at certain times of the day? Are certain exchanges worse than others for withdrawal fees?

I’m my case, I just tried a test send of $30 of our grand daddy blue chip from crypto.com app to trust wallet. When it got to trust wallet it was only $20 worth. I’m so confused. If I sent a larger amount like $100 or $1000 would the fee be the same? Would it be larger?

Also, I have a ledger ordered from their website on Black Friday. Would you recommend waiting for the ledger or getting the crypto off the exchange right now and then sending from trust wallet to ledger later when it arrives?

Anyway, I apologize if there’s somewhere else I should have posted this. If that’s the case please let me know. Thanks in advance for the advice