Just bought tickets on Thalys for this Autumn

I can't help you with the Schiphol location of the Thalys location within that station because we boarded our Thalys train one stop before you at Amsterdam Central in May. What I can tell you was that there seemed to be one designated track for Thalys and there was no extra security or screening at Central. It was helpful to be there a good 15 minutes early because the train is long and we needed time to find our car once it arrived although there was a chart near the track which told us the approximate car locations. There was extra scrutiny of disembarking passengers when we arrived in Paris and we all had to walk single file through a group of police and dogs. We were on the 13:15 train but I think they do this with all Amsterdam-Brussels-Paris Thalys trains.

We too booked seats across from one another and had to switch as the train started up. Our seat mates laughed because they had the same motion sickness issue too.

At Schiphol airport the Thalys uses one of the regular underground platforms (5 or 6) and just has a short stop. Be there 10 minutes before departure time.

My experience with Thalys: Traveling from Paris to Amsterdam from Gare du Nord a line began forming inside the front of the station in a little red roped off area about 20-30 minutes before boarding. We had gotten there a little earlier and stood out front in the morning coolness until about 10 minutes before boarding. Security was fast - plopped our bags up on the conveyor belt and met them on the other side and went directly to our car. Very quick and efficient compared to airline security.
We also were at a table. We found the ride very pleasant and it really didn't seem we were on the train that long.

Have a wonderful trip!

We took Thalys from Gare du Nord to Amsterdam Centraal station in late April. We bought first class tickets and we did not have to take our luggage through security.
We arrived at the station 45 minutes early just to be on the safe side and had no issues with finding where our train was boarding, etc. I noticed passengers going through security who were not first class ticket holders. I think I would arrive at least an hour early before your departure time.
Btw, I bought first class accidentally, it was my first time purchasing train tickets! Very comfortable ride!

I appreciate the feedback so far. Thank you! I hope I don't have to arrive at Gare du Nord 1 hour in advance as our Sunday morning train departs at 07:55. I was hoping we could arrive 30 minutes early.

How is the platform signage at Gare du Nord? Or is it simply looking for that red roped area as was described already? I'm guessing there is more than one Thalys train early Sunday mornings so I should not assume that if I see a red rope area that it is for our train. Am I correct with that assumption?

Thanks for the info about platforms at Schiphol, tonfromleiden. That sounds easy.

I appreciate the feedback so far. Thank you! I hope I don't have to arrive at Gare du Nord 1 hour in advance as our Sunday morning train departs at 07:55. I was hoping we could arrive 30 minutes early.

How is the platform signage at Gare du Nord? Or is it simply looking for that red roped area as Nance described for her train to Amsterdam? I'm guessing there is more than one Thalys train early Sunday mornings (ours heading for Dortmund) so I should not assume that if I see a red rope area that it is for our train. Am I correct with that assumption?

Thanks for the info about platforms at Schiphol, tonfromleiden. That sounds easy.

The international trains at Amsterdam Centraal arrive and leave from the back of the station along the river IJ. I find the signage at Centraal confusing when first entering the station.
At Gard du Nord the signage is good, big boards easily read! Like you, I wanted to make sure beforehand that I knew what was what and where was where, so I had researched where to go, both arriving on Eurostar and leaving on Thalys. There is a big board inside where you can find your train and it will tell you which track your train leaves from. Thalys has red engines so you can't miss them, and they run on tracks 7 and 8. Both Eurostar and Thalys are on the left side as you enter the front of the station. As I recall, we walked in the front doors, past some little booths either side, and as we moved into the station there were the Thalys trains on our left. There wasn't any line up area at first and we stayed outdoors where hubby could smoke and we could people watch. About 20-30 minutes before leave time we re-entered the building and the roped out area was formed. There was an employee there directing people. Here's a page where you can see pics of the station. Look for the red trains: gare du nord