To be fair the whole Waterloo, Kings Cross morning and evening commuter peak thing isn’t new, and the simple fact is there are more commuters than bikes/spaces in the peak commuting hours.
Since the scheme launched TfL/Serco have installed new docks around Waterloo and extended others. They have also installed a storage cage area in Waterloo station to facilitate extra bikes during peak times. The end result is a much improved experience on the original situation (read last years posts on the same subject) however you will experience difficulty at Waterloo during the times you mention.
Remember the bikes aren’t set up to take the huge commuter demand London faces everyday and that using them when you’re maybe not so pressed for time will result in a much more enjoyable experience.