Road work is always a good thing. The important thing, as far as fitness is concerned, is to keep the crank turning.
Morning or evening rides boil down to personal preferance. I like 'em both, when I can squeeze them in. Mornings because the air seems sweeter, the birds singing just for me, the traffic less congestive... Evenings because, watching out for the attention-challenged drivers notwithstanding, I can clear my head of the days worries and stuff.
I'm not even close to being an expert on this sorta thing but, if'n it were me, I'd do my road work closer to the time of day that I'd be exerting myself.