Set as a featured image in each post - about 800 post in total

I have a site with approximately 1,147 post with about 800 post in which the featured image missing .

What I would want is who ever is assigned the job goes in alphabetical order or which ever way is easy for him or her to add featured image in the remaining post and update it

(image will be provided ) 800 image would be around 25 MB . so upload wont take more than 10 seconds for each upload!!

My easy way of doing it
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I choose the file >>click rename >> copy the file name >> go to post search with the file name and search the related post.

get the post and edit and add the featured image !!

note while searching for a post the image related would be "Ashby Woulds_opt" and the post name would be "Ashby Woulds"

I will give the information once i choose my right person for this job!!

DEAD LINE IS A MUST HERE . PLEASE ONLY APPLY IF YOU ARE CONFIDENT ON HOW YOU WILL DO IT AND NOT ON WHAT YOU ARE DOING!!

IN ANY CASE MISSING THE DEADLINE IS NOT ACCEPTABLE !!

it will be 48 hours from the time I would accept the proposal and pass on the details to you.

if you need a screen shot or a full explanation on what is to be done ask till your are clear of the job.