Train journey time from Asakusa to Nikko?

We're planning a day trip from Tokyo to Nikko, focusing in particular on the Okunikko area.

We want to get the Nikko All Area Pass for this, which entitles us to a round-trip from Tokyo, but can't find any information about how long the journey is, or train timetables. Can anyone help? We want to set off nice and early to squeeze everything in, but need to know what we're working with. Do we need to reserve tickets, or is that only for the 'Limited Express' trains?

Thank you.

It is explained here:
https://www.japan-guide.com/e/e3805.html

The entire timetable for limited express trains is here:
http://www.tobu.co.jp/foreign/en/using/timetable.html

Or you can use Hyperdia (the station in Nikko should be entered as "Tobu-Nikko"):
http://www.hyperdia.com/

I normally work on two hours for Tokyo to Nikko and up to the lake another hour by bus (slightly shorter, but allowing for some waiting time and at weekends traffic makes it longer).
The direct express (Kegon) is 108 minutes.

Thanks for your answers, though the information about the non-limited express trains is still unclear. All trains to Nikko seem to be Ltd. Express, not the 'local' trains that are included in the Nikko All Area Pass.

We think we'll pay the extra for the Ltd. Express tickets anyway. We only have the one day at Nikko, so it's best if we keep the journey as simple as possible...

To whom traveling with Tobu Nikko Pass all area,
a 20 percent discount is given on the Limited Express surcharge.
You can check the conditions on the website of Tobu Railway.
http://www.tobu.co.jp/foreign/en/pass/all.html

According to the current timetable,
the earliest Limited Express train for Nikko
is Revaty Kegon 1 departing at 6:30 from Asakusa Station,
which is to arrive at 8:22 in Tobu-nikko Station.
The surcharge is 1160 yen after the 20 percent discount.

Alternatively you can take the following two trains,
in which case no fee is required in addition to the basic fare (covered by the pass).

Asakusa
( 6:44)
| [Section Express]
( 7:52 / 7:53, depending on days)
Minami-kurihashi
( 8:00)
| [Express]
( 9:16)
Tobu-nikko.

Do we need to reserve tickets, or is that only for the 'Limited Express' trains?

Seat reservations are mandatory for limited express trains, but are not possible for other trains. If you don't want to take a limited express train, you can look up connections by de-selecting "limited express trains" in Hyperdia. Note that there are no direct connections, and at least one transfer is required along the way:
http://www.hyperdia.com/