If you want to hatch the egg make sure that you have:a trap/a house near the trap/wyvern spawn location near the trap.
If you are a begginer you need to know that getting milk is pretty easy but with no ytap makes it a nightmare.Good Luck!
I got a level 150 lightning egg and I was so excited to hatch the egg...that when I went to put the egg down I accidentally ate it instead. :( ps4 users: R2 ISN'T GONNA DROP THE EGG YOU'RE GONNA EAT IT LIKE ANY OTHER EGG. REMEMBER THIS. LOGIC BEFORE EXCITMENT.