Yes, I believe that is time for Senator Elizabeth Warren to endorse one of the Democratic party candidates because she is a respected leader in the Democratic party and the party needs to unite as one and support one candidate. I believe that Warren is going to endorse Hillary Clinton because she is the front runner and looks poised to win the nomination.
Elizabeth Warren is a very popular member of the Democratic Party, and I can understand why she would hold off on making an endorsement. She may not want to put herself in the middle. She may want to wait until a nomination is made. Someone like her needs to stay out until there is one candidate, so as not to create a rift in the party. Imagine if she endorsed Sanders, and Clinton won the nomination. During the general election, this could hurt Clinton because Warren didn't choose her first. Elizabeth Warren will make her endorsement when the time is right, and not a moment before.
Elizabeth Warren is a power punch in a skirted suit. Considering how outspoken she is about practical governing, it would behoove her to wait until she is absolutely sure her endorsement will do the most good. Right now, she's dressing down Republicans who have been taking free money for not doing their jobs and who are still getting away with it. She knows what she is doing. Give her time.
Senator Elizabeth Warren would be wise to hold off endorsing a Democratic candidate for president. There is no benefit to her or the party by doing so now, particularly since it is unlikely to be contentious. If she did make an endorsement, it would only serve to make the party battle more divisive. She will support whomever the nominee may be in the general election.