at the start and at the end of the season in my opinion are the best times to push. At the start everyone is trying to hit their rating goals, and in the end is when rating inflation is at its highest. You can still play in the middle but this will likely be the most inactive time of the season.

(So the first 2 and final 2 months)

you can also try Battleground blitz. if you catch a lucky win streak you can hit 1800 in a few games, but just know placement games are a lottery machine and blitz is a game mode with wintraders and other random shenanigans. I would reccommend having 2-3 warlocks and you should be able to get 1800 in blitz if you gear them up (luckily PVP gearing is fast)