Considering three aspects: itinerary arrangement, transportation mode and accommodation, the best time to visit Jiayuguan should be between 9 am and 17 pm.

1. Itinerary: The main tourist attractions in Jiayuguan include Jiayuguan Pass, the Hanging Wall and the first pier of the Great Wall.

Based on the distribution of attractions and travel time, the recommended itinerary is as follows: visit Jiayuguan Pass from 9 am to 12 noon, visit the Hanging Great Wall from 12 pm to 4 pm, and visit the first pier of the Great Wall from 4 pm to 17 pm.

This arrangement can make full use of time, avoid hot weather, and make the trip more comfortable.

2. Transportation: The transportation in Jiayuguan is relatively convenient. Taking a taxi or chartering a taxi in the city are both good choices.

If you only plan to visit the Jiayuguan Pass, the Hanging Wall and the First Pier of the Great Wall, it is recommended to rent a car to go there. This will make it easier to go to various attractions and save time on the road.

3. Accommodation: It is recommended to choose a hotel near Datang Food Street for accommodation, which can not only facilitate the night's rest, but also facilitate the daytime travel.

To sum up, the best time to visit Jiayuguan is from 9 am to 17 pm. This time period is the best choice for visiting Jiayuguan.