K-1 capital gains timing for annual method penalty calculation

I received a K-1 on March 30 indicating significant capital gains. Without these gains I would not owe additional federal tax beyond what was withheld. However, since the gains are significant not only do I owe taxes on these gains, but I also owe a large penalty. I would like to reduce my penalty by using the annual method. Since I received the K-1 on March 30 would I say the gains occurred in the last quarter of the tax year? It doesn't say when the LLC actually received these gains and even if it did I would not have known until the K-1 was sent to me. thanks.