I typically try and stay away from the I Fund, the fundamental factors are very difficult to keep track of and the technicals swing very wild with our indicators.
Have you been able to find an indicator that consistently provides great entry points?
Here's my take on this situation and background info for your future TSP decisions...
When regression to the mean in the US$ happens, this development will be positive for I Fund along with C Fund, to a lesser extent. S Fund will then have a headwind to contend with.