P.S. It takes 750TH to bring the possibility (considering 100% luck) under one week per block.
P.P.S. If 28TH had a reasonable possibility of finding a block in a month, more people would be soloing.
P.P.P.S. The above numbers are only good for another few days - then it gets 10-20% harder.
P.P.P.P.S. If you want to mine solo, you can still do it reasonably using what ASICs you can find for scrypt and mine LTC. With a good 10K investment in rigs you would likely be able to solo LTC blocks in under a few days. Of course, each one of those blocks is currently only worth $75. Historically, LTC follows BTC, meaning as we wind closer to the halvening of BTC, most people are predicting a meteoric rise in BTC prices and if that happens, it's entirely possible (some say probable) that LTC will follow BTC to the moon. Hint... hint...