Does anybody use 
to charge the N26/Monzo account by transfer? I wonder how is the average time for the transfer between these online entities?
I do. It is instant.
Which one Monzo or n26?
For me 1 day to N26 and 30 minutes to mz. But with Monzo you can top up by card or make a payment link and pay with your revolut card instantly.
I was referring to Top-Uping via N26 card into Revolut Account.
Never tried transfering funds over SEPA payments, but it should be around a day or so.
Typically a day, though most banks expect the transfer before some cut-off time. Also weekends and holidays are excluded. So if you wire it on Friday at 4pm and Monday is a holiday, there is a good chance it will be wired on Tuesday and arrive on Wednesday.