Never wait to write up research notes from your trip. Write up your temporary conclusions, things you notices, items you need to pursue further, etc. as soon as you can. You will forget why you looked up certain items and those unclear notations you made that you “would never forget” will be forgotten.
Time spent writing up your notes is not wasted.
Wasted time is what is spent later trying figure out why on Earth you did certain things or in spending an hour to reach the same conclusion you did earlier a week ago when you were actually researching.