Theresa May seems to be taking a cautious approach to invoking Article 50.
"I have already said that I won’t be triggering Article 50 until I think that we have a U.K. approach and objectives for negotiations. I think it is important that we establish that before we trigger Article 50.” - Theresa May
This ties in with how what we've seen of her before, that she'll take a measured approach to the job at hand. However it may well upset other who want Aticle 50 to be invoked as soon as possible. Hopefully she won't be intimidated by them and will do it at the best possible time for the British people.