Considering the fact that you intend having a long term investment, i will suggest that you buy, knowing that whenever there is a drift in price, it will eventually go back up. Also, considering the fact that the market is currently at a support range, i think you should buy.
Long term investors can easily decide to keep buying the coins since they know that the chance of rise is possible if you can patiently wait.
There's no exact position since there's a lots of market movements what you need is to have a good knowledge from doing your research
and keep being updated so you'll be able to understand all the risk and all the potentials that you can get from your investment.