Sort:  

The easiest way is to increase your SteemPower quicker than having to wait a week for the payout.

Otherwise, by having the Steem (or SteemPower) in your account, you can use your SBD to promote, rather than converting it to Steem and then Powering Up.

Used correctly, I've been able to get roughly 2 Steem/SBD for every 1 SBD I've used to promote. This should cover the interest rate.

Coin Marketplace

STEEM 0.29
TRX 0.12
JST 0.032
BTC 63122.36
ETH 3072.69
USDT 1.00
SBD 3.86