Master blindfold chess in 6 months I want to be able to play entire games blindfolded, atleast at the strength that I can win against beginner players. My current ELO is around 1800. I usually manage to play ok moves up to move 20, after that I struggle to see the position clearly, and have a hard time finding moves at all.

Is 6 months a reasonably timeline to expect substantial improvements? What would a good strategy be to achieve this goal?
If you spent roughly an hour a day for 6 months, then it's absolutely reasonable at your playing strength. The only chess-related thing you have to do is just practice playing blindfolded. Gradually it'll become more natural.

You could also do exercises for improving your overall memory (so not just related to chess). Such exercises are outside the scope of this community, but I'm sure you can find many online.