MFCC delta: How to compute delta, in real time, with no future frames?
As long as you train and evaluate the same features then you will be perfectly fine with this delay. 

In practice first two frames of the feature vector for both $\Delta$ and $\Delta\Delta$'s are zeros. So in fact the coefficients are delayed by two frames. These can be calculated according to the formulas:

$$\Delta[t] = c[t]-c[t-2]$$
$$\Delta\Delta[t] = c[t-2]-2c[t-1] + c[t]$$

Notice that the scaling factors are omitted intentionally. It's only a linear scaling of the feature space and should not change the results. For example in the case of GMM's the Mahalanobis distance takes care of differences in variance across dimensions.