If HTML already exist then 2-3 weeks.
Coding can be finished in ten days or less but design process with all rejections can take anywhere from 7 days to few months.
Your theme can be improved in terms of design. Slider doesn’t look “premium”, slider text is not visible, overall typography can be better and more appealing, three columns below slider look dated etc. Try to work more on details (I suppose it is rejected because of design).
Design needs more work, it looks dated, has basic design problems with spacing and typography (icons too big, main headlines too small etc.), rotated image doesn’t look good and animations are not good but design should be in the first place for improvement. It just needs more work, compare it with other new themes approved here and try to find difference.
I don’t know much about travel booking templates but if your template preview and template description doesn’t have and doesn’t list that feature you don’t have any fault. If other templates don’t have that feature how could customer said that other templates he bought had that?
It is not your fault. But it is good experience. For every niche there are some features that customers expect and sometimes don’t even check before purchase, that is the case here. If you already don’t have a feature that is common for that niche you should explain that in your template description. Sometimes it is good even to explain if template is HTML and not WP theme.