Hi.. this is the same question that i always think about.. but there is a slight difference.. I always prefer writing after travelling but I usually jot down the name of places, attractions and other things so that those can prove useful later.. However you can choose between both as per your convenience..
Writing after travelling is a better option as you can write about the experiences while traveling and the way you felt about the place and everything.
Hey Snehal, I always jot down my experiences on a day-to-day basis in a journal and then I write about my trips on Tripoto after the trip. It makes you remember things well, and you can always improvise later!
You can write some important notes while you are travelling,whereas the entire blog can be written later..that gives you more scope to enjoy your trip and not forget important places/experiences while you were on trip
I generally enjoy my stay take a lot of pictures and videos and when am back i post a blog with all the awesome pictures as part to it.
Also helps to have videos uploaded to youtube or insta