Sumatra logistics

I've done only the BL to Brastagi 1-2 yr ago on a shared taxi basis. The taxi driver informed me he will continue on towards Parapat Tigaraja harbour where you will connect with the last ferry to Tuktuk. There were 3 other passengers that continued with the journey after I got out in Brastagi.

If you go to Danau Toba you would normally go to Tuk Tuk on Samosir Island by ferry which closes about 18:00. You can go there (to Parapat where the ferries depart from) and stay in a hotel till morning. On the other hand you can go to BL -- you will get there late but you get to your accommodation. You definitely need to prebook your accommodation and probably organise your transport through them. Go around the circle in one direction or another. Not sure which is the better direction at that time at night.

Yes -- you can go between the two in one day. This might mean going into Medan -- you have to discuss this with your driver or your booking agent (and make sure that they are in sync).

There is accommodation near the airport but I don't know where it is. You obviously know the difference between Medan and the airport (about 35 km, one hour between them) -- better to say KNO (Kuala Namu) when referring to the airport on TT to improve clarity.

Paul

I would take a taxi directly from the airport to Bukit Lawang upon arrival.

From Bukit Lawang to Lake Toba is around 8 hours, so a full day really, tourist bus best option, or private car if you're flush. It's closer from the airport but it makes more sense to go directly from airport to Bukit Lawang than to use the next day for travelling. You can't reach Toba the same day from the airport due to lack of ferry crossing late at night.

There's no sense at all in staying at the airport, pay for the taxi and get cheaper accommodation in BL.

Btw the ferry from Parapat Tigaraja to Tuktuk will drop you off at the pier nearest to your accommodation. So if you know the name of the gh, inform the ticket man onboard when he comes to sell the ticket. I think the last ferry to Tuktuk is about 7pm.

yes the last ferry is 7pm, though there is a 9pm car ferry (but it doesn't drop you to your guesthouse you need an onward pickup from there) from a nearby (2km) port

That 9pm ferry is Ajibata to Tomok?

Yes.
There is the option of staying the night in Parapat and cross to Tuk Tuk first thing in the morning.
I agree that going to BL first is the better option though it might be hard to find transport at that time of night -- as I suggest prebook your GH and organise transport through them.
Paul

Thanks for the replies. I would rather stay in Medan the night and get transport to BL the next morning. I’m sure by the time I get out of the airport it would be almost 21:00.
Is it easier to reach BL ( public/ shared transport) from Medan city or airport?

It is hard to get any transport except the public buses from Medan which are controlled by thugs -- I don't suggest you use them on your first time. Talk to your GH is best. The airport would be best. Or reconsider going to Parapat and spend the night there -- there are some reasonable hotels there -- don't use the one near where the ferries leave from. (cheap Charlies?)

Paul