Should I flip to flower

It'll probalbly overfill that space before stretch is done. Could probably flip a bit earlier next time... You want roughly half the space filled at flip. This is a bit different per plant -- some stretch more than others. you can combat that by continueing to train lanky plants longer into flower than you do with bushier/shorter plants. Let the bushes go vertically immediately after flip, but train the lanky plants down an extra 3-10 days depending on how lanky they are. This delay will result in an even canopy without too much work. Could top them a bit after flip, too. Use whatever tool will most effectively result in the shape/growth pattern you want. 70% x 70% = 49%, or roughly 1/2 your space... So 70% of length by width dimensions is a good time to flip. You can always prune off congestion or overcrowded areas if it does overgrow the space. Keep it healthy.