It's universal "law" of all trading: Buy low, sell high.

Yes, buy STEEM for your SBD when the STEEM value is low.

The big question is, when do you think it's at it's lowest? =)

I do not want to give advice on when to buy, as I have only my subjective feelings of the market to base it on.

I'm in it for the long term. Day trading is not something I wish to spend time on.