It is not the matter of "giving Trump a chance". There is no need to be obstructionist - if he proposes something non-controversial, it should be treated on merits. However, much of what he is likely to do is going to be the direct assault on liberty and democracy. The role of the opposition is to oppose this. If Dems do not do that, they will abdicate their direct responsibility.
In any case, Trump has a Republican majority in both chambers. Dems can´t really do much, except raise their voice whenever necessary.
It's open season on the budget, but Democrats can still block other things just like Republicans did even when Democrats had just shy of 60 votes in the Senate. As long as that cloture threshold remains, there won't be massive policy changes without Democratic approval.
However I agree with what you're saying. If he proposes something good, like an
effective infrastructure plan
(and not just wasteful tax incentives), I'm all for that. I don't want my party pulling some sleazy obstruct-everything strategy. If he tries to push massive tax breaks for the wealthy, changes to things like HAVA, or privatize [federal program], I fully support and demand that my party do whatever it can to block it.
But I will never respect this monster nor will I ever personally give him a chance. As far as I am concerned, he's just some sexual predator scam artist that I have to put up with for 4 years.