Hi- if the plants are healthy they will begin to produce flowers and fruit soon. If you know the variety you can look up the expected maturity date- time from seed sowing to first harvest.

Most Persian or Beit Alpha cucumber varieties produce only female flowers and do not require cross-pollination to produce fruit. It's possible that flowering occurs a little bit later with this type of cucumber.
Jon

Hi here is some photos of the vines. They seem healthy to me but no flowers. Is there a chance this could be a weed instead of cucumbers? I have had violet in the plot, but the leaves are shaped different and my plant ID app says this is cucumber. It aligns with here I planted it. 

Hi- these appear to be cucumber plants. Depending on the variety and soil and weather conditions, plants should begin flowering 4-5 weeks after planting seed.

Plants should be spaced at least 12 inches apart. Crowding will reduce flowering and fruiting.
Jon

It’s probably been about 8 weeks since planting seeds. These are Persian cucumbers. 
Sent from my iPhone



Hi- the only weeds that come close to resembling the plants in the photos are morningglories and bindweeds:
https://cals.cornell.edu/weed-science/weed-profiles/morningglories

https://cals.cornell.edu/weed-science/weed-profiles/bindweeds

They would have white or purple flowers. Cucumbers have yellow flowers. 
Jon

Hi, I emailed about a month ago to ask about my cucumber plants vining everywhere but not flowering. They started flowering recently and are producing these oblong super spiky fruits. I thought I purchased a version of Persian cucumbers, so this is surprising. We inherited the garden plots from the previous owners and I cleared them. However, also wondering if something they planted regrew and it’s not a cucumber at all or is a toxic fruit. The plant ID app I use lists it as an African-horned cucumber. 

Hi- the fruits appear to be jelly melons, aka African horned cucumber- Cucumis metuliferus.
Jon