Tried to build in some margin for error by waiting till the 20th. Most years the last part of April seems to signal sustained warmth(50-70F) and spring like temps. Grass starts growing and can purchase flowers to be planted around Mother's Day.
Pretty much what I expect every winter. Exceptions happen like 2007-08,13-14 etc. Trend seems to be eliminating December as a winter month lately. Not sure if March and April will make up for lack of activity in December.