It would've taken me maybe 2-3 more weeks to add all the missing functionality, handle all edge cases, and polish the UI. There really isn't that much to it. I've participated in Pavel Durov's contests[1] where you had to make a Telegram client in a month given only a networking/database library. (in that particular contest, I skipped the 1st round, so I had to catch up in 2nd)

[1] https://vk.com/wall-55882680_74 (in Russian)