I don't think it matters if you take a daily dose vitamin D every day or a larger dose once a week. Some doctors prescribe 50,000 IU of vitamin D in a pill to be taken once a week. That is just over the equivalent of 7,000 IU per day. The advantage is that since it is prescribed then your health insurance may pay for it.
But those prescript
ion vitamin D pills are usually vitamin D2, which is an artificial form of D. You can very cheaply buy vitamin D3 over-the-counter which is the natural form of vitamin D.
Your blood level was about
25 ng/ml, the ideal level for disease prevention is from 40 to 60 ng/ml. Over 100 ng/ml is flirting with overdose. Check out the following website:
grassrootshealth.net/The chart on the top right of this web page explains how much extra vitamin D is needed to reach optimum levels depending on your current blood measurements. Since your current level is 25 ng/ml then to get to 40 ng/ml you need an additional intake of 4,000 IU/day.
This applies for the average intake observed to produce noted serum levels in adults, 150 lbs average weight. Averages only. Since everyone is different you should get your blood levels checked again after supplementing for a few months, or as Dikid said after 6-8 weeks.