Can I import my Google Maps Timeline?

Not directly. Timeline can show you the dates and places of old trips, which you then enter as stops. Import of GPX and KML files is planned.

How do I find the date of a photo?

Open the photo and look at its details or info panel. Phones show the date, time and, if location was on, a map. Photos received through messaging apps often lose this data, so use the original.

Should I add home as the first and last stop?

Add it if you want the distance to include getting there and back. Leave it out if you only want the route within the destination. Whichever you choose, do the same for every trip so the totals are comparable.

How to Rebuild Your Travel History From Old Trips

Start with your photos: every phone picture carries the date it was taken and usually the place. Then fill the gaps with booking emails, airline and hotel account histories and passport stamps. An evening is normally enough to recover ten years of trips to within a few days.

Sources, from most to least useful

Source	What it gives you	How far back
Phone photo library	Exact dates, and places when location was on	As long as you have had a smartphone
Email search	Flight, hotel and rail confirmations with dates and cities	As old as your mailbox
Airline and hotel accounts	Past flights and stays under your loyalty number	Often several years
Passport stamps	Entry and exit dates for countries that stamp	The life of the passport
Location history	Day-by-day places, if you had it switched on	From the day you enabled it
Bank and card statements	The first and last foreign payment of a trip	Usually up to seven years

A method that works

List the trips you remember, one line each, without dates. Order does not matter yet.
Open your photo library, switch to the map or places view, and note the first and last photo date for each destination.
Search your email for words such as itinerary, booking, e-ticket and reservation, together with the year or the city.
For trips before your first smartphone, check old passports, printed photos with dates on the back, and people who travelled with you.
Enter each trip with its name and dates, then add the cities in the order you visited them.

When you cannot find a date

Enter the trip anyway. A trip without dates still shows its route and counts toward countries, cities and distance. If you know the year but not the days, use the first of January to the same day: the year table will be right, and one day adds almost nothing to days travelled. You can correct it when an old ticket turns up.

Order of stops

The route is drawn in the order of the list, so the order matters more than the exact dates. If you flew into one city and out of another, put them first and last. Day trips from a base can be added as stops in between or left out; both are honest as long as you are consistent.