Here's an example. i just did my first mass evolve with a lucky egg. Managed to get 69000 XP. 

Before	After

2 things of note:
1. Set your own 30min timer because you can't see the timer when doing the evolves.
2. Don't exit to the map screen for whatever reason because if you have leveled up, the level-up animation will waste precious seconds.

lv1 - lv 15/16 is very easy, but u need to spend time on grinding pokemon
imo only use this trick from lv17-lv20, coz each lvl u need 20k 20k 25k exp

i started playing on weekday due to working no time to camp haha
one day after work i spend about 2-3 hours at pyramid just to catch whatever i see for the (100exp) from lv2 - lv 8
then some casual playing get to lv10, and last weekend i camp at KLCC from 10am - 6pm lv10 - lv 16, and few hours in pyramid to lv17
after that i only spam lucky egg too lv20 total process in hours i think took less than 24 hours and im now lv20

but yeah lv1 - lv 17 is kinda easy but anything beyond lv20 is gg lol     

sorry, i think my question was not that clear.

1) i meant to ask if you guys, during mass evolve (lucky egg time), will choose to evolve pidgey that only has a CP of 10?

2) should i plan my mass evolve after i managed to catch/accumulate 400 magikarp candies? if i mass evolve now and level up to, say, lvl20, it will be harder for me to catch pokemons. therefore, i wanted to know if it is better to accumulate 400 magikarp candies first before proceed to use lucky egg for mass evolve to increase my trainer level?

Wow, nice! How many evolves did you do? Was it 77 with no new pokemons or less with new pokemons registered to achieve the 77k XP?