However, after shooting down England for just 58 in the first innings, they should have plenty of time to wrap up the contest unless dramatic amounts of rain saves the visitors the blushes.
It was saved from more grave humiliation by tailender Craig Overton.
His overnight partner Nicholls progressed to 49 not out with Watling on 17 when rain again sent the players indoors for a second time - midway through the second session of the day-night Test.
"It was a good start to the match, nice to get the ball swinging around a bit and see a couple of knicks go through as they did", Boult said.
The hosts had bowled England out for 58 on the first day.
The England bowlers found some movement when they took the new ball one over after the tea break, and within five overs had the wicket of Williamson. They are now leading by 171 runs with six first-innings wickets in hand.
He faced 220 deliveries to bat New Zealand into a position of dominance with partnerships of 84 with Tom Latham, 31 with Ross Taylor and 83 with Nicholls.
Anderson continued to be the pick of the bowlers with three wickets, while Stuart Broad's lone wicket was a special one as it was his 400th wicket in Test cricket.
It figures that Williamson will probably be looking to the evening session tomorrow, when he will be able to unleash Trent Boult and Tim Southee with the new pink ball under lights. The wicketkeeper, however, was fortunate that the throw from Chris Woakes was wide.
When play resumed more than an hour later, he added only two further runs before being dismissed leg before. The first and second wickets fell with the total 6, the fourth, fifth and sixth at 18 and the seventh and eight at 23, leaving England in danger of recording the lowest-ever total in test cricket.